Vocal Function in Subjeets with Compensated Unilriteral Vocal Fold Paniysis Pre and Post Mediabation Thyroplasty
Jennifer Ann Anderson MD FRCS(C)
A thesis submitted in conformity with the requirements for the degree of Master of Science
Graduate Department of Speech Language Pathology University of Toronto
Q Copyright by Jennifer Ann Anderson (1999)
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Vocal Function in Subjects with Compensated Unilateral Vocal Fold Paralysis
Pre and Post Medialisation Thyroplasty
Master of Science, 1999
Jennifer Am Anderson
Department of Speech Language Pathology
University of Toronto
ABSTRACT
Unilateral vocal foId paralysis is a condition that can cause signiscant vocal dysfuaction.
Treatment options include behavioural therapy or surgical procedures. The purpose of the
present study was to investigate specific vocal function parameters in subjects with a
compensated unilateral vocal fold paralysis, and to investigate the effects of mediaiïsation
thyroplasty on these parameters. The pathophysiology of the voice abnormality
associated with a unilateral vocal fold paralysis and the relevant literanire regarding
treatment has been reviewed. Measurements included indirect laryngoscopy, acoustic
data (fiindamentai fiequency, percent j itter and shimmer), fundamental ftequency and
intensity range, voice range profile, phonation threshold pressure, perceptual evaluation
and a reading task. Results inâicated that most subjects exhibited a reduced fiuidamental
frequency and intensity range compared to normal values prior to surgery. A cornparison
of data fiom before and after medialisation thyroplasty indicated that most subjects
showed improvements in the vocal parameters evaluated.
Many of my evenïngs and weekends were devoted to completing course work and
preparing this thesis- My husband, Andres Gantous, not only contnbuted excellent
diagrams but also provided emotional support mixed with a great deal of patience over
the past three years
My two children, Alexis (age 4) and Ariana (age 3) were also participants at one
time or another during this graduate work and they ofien 'helped' when 1 was working on
my laptop. My second daughter, whose arrival is pending, was quiet and attentive during
my defence. My parents have been incredibly generous with their tune and have enriched
my children's Me with their support particuiarly when Mom was studying.
The author would like to formally acknowledge the invaluable guidance of Dr.
Cannen A. Ramos Pizarro, without whom the thesis wodd have suffered in quality and
style. Also, my s u p e ~ s o r y committee members, Dr. L. DeNd, Dr. S. Abel and Dr. P
Doyle, 1 would like to thank them for their guidance and sharing their expenence.
Phi1 Doyle was a reassuring resource of knowledge and encouragement. The
members of my defence cornmittee inchded Dr. C. Dromey, Dr. C. Johnson and Dr. H.
Kunov as well as my supervisory committee members and are acknowledged for the t h e
and effort to review the manuscript.
Finally, Lon Tenuta deserves many thanks for the hours of assistance typing this
manuscript and helping me understand the mysteries of word processing.
TABLE OF CONTENTS .. ABSTRACT .............................................................................................................................. n ...
ACKNOWLEDGEMENTS ..................................................................................................... ill . . LIST OF TABLES .................................................................................................................. vli ... LIST OF FIGURES .................... ... .................................................................................... m LIST OF APPENDICES .............................. .....-.. ......,............ . ix CHAPTER I ............................................................................................................................ 1 INTRODUCTION ............................ ... ............................................................................. 1
Overview ....................................................................................................................... 1 Purpose ...................................... .... ........................ 2 Laryngeal Anatomy ............................ ... ................................................................... 2
.............................................................................. Laryngeal Muscle Function 2 Innervation of the Larynx ................................. .. ........................................ 3
Natural History of Unilateral Vocal Fold Paralysis ftom Recurrent Nerve Paralysis ................ ... ............ 7 Vibratory Characteristics and Stroboscopy in Unilateral Vocal Fold Paralysis ........... 9 Theoretical Effects of Unilateral Vocal Fold Paralysis on
.................... ............................. Fundamental Frequency and Intensity .... 11 ................................................. Physiologic Control of Fundamentai Frequency 11
............................................................................................... S W e s s (Tension) 11 ................................................................ Thyroarytenoid Muscle Contribution 12
................... ..................................................................................... Length ... 12 ........................................................................................ Subglottic Air Pressure 13 ..................................................................................... Behavioural Mechanisms 13
........................................... ........ ........ Fundamental Frequency Range .... .... 14 Intensity ............................................................................................................. 14
............................................................ Treatment of Unilateral Vocal Fold Paralysis 15 ................................................................... Augmentation of the Paralysed Fold 16
................................................................................... Medialisation Thyroplasty 17 Theoretical Effect of Thyroplasty on Fundamental Frequency and Intensity ............ 18
........................ Literature Review of Vocal Effects M e r Medialisation Thyroplasty 19 ....................................................................................... Stroboscopy Evaluation 19
............................................................ ......................... Acoustic Parameters ..... 21 .............................................................................. Fundamental frequency 21
............................ .............................-..... Perturbation measurements .. 22 .................................................................... Fundamental frequency range 22
................................................................................................... Intensity 23 ................................................................................... Voice Range Profile 23 .
....................................................................... ................. Aerodynamics ....... 24 ....................................................................................................... E ffoflatigue 25 . . .................................................................................... Perceptual Charactenstxs 27
................. ........................................................*................................- Summary .. 27 .................................................................................................. Research Hypotheses 29
......................................................................................................................... CHAPTER I1 30 ................................................................. ..................... METHODS AND MATERIALS ... 30
................................................................................. ............ Study Design .......... 30
Participants ......................................................................................................... 30 Medical Evaluation and Data Collection of Participants ............................................ 33 Videostroboscopic Examination ................... ...... ................................................. 34 Acoustic Data Collection and Analysis ................................................................... 35
Fundamental Frequency Range .......................... ... .......................................... 36 Voice Range Profile .............. ..., .......................................................................... 37
Aerodynamics ........................ .............................................................................. 41 Effort Data ........................ ... ................................................................................... 41
Phonation Threshold Pressure ........................ ..... ...-........ ........................... 41 ....................................................................................................... Reading Task 43
Percepnial Effort Rating ...................................................................................... 43 ..................................................................................................... Listeners 43
Procedure (Construction of Stimuli) ......................................................... 44 S tirnulus preparation ... .. .................................................................... 4 4 Perceptual evaluation ..................... .. ........ ......... ......................................... 44 Data analysis ....................................................................................... 4 5
C W T E R III .................................................................... 4 6 RESULTS ......................................................................................................................... 4 6
Acoustic Data .............................................................................................................. 46 Fundamental Frequency ........................................ ... ..................................... 46 Perturbation Measutes ................................................................................... 47 Fundamental Frequency Range ............................... ... ... ., ....................... 51
........................................................................... lntensity Range ................... .. 53 Voice Range Profile Area ................................................................................. 55
Aerodynamic Data ..................................................................................................... 60 Effort Evaluation ................ ,., ..................................................................................... 62
Phonation Threshold Pressure ........................................................................ 62 Reading Time ................................................................................................ 67 Perceptud Effort Rating ...................................................................................... 70
........................................................................................ CHAPTER IV ......................... ... 72 ....................................................................................... ....................... DISCUSSION ... 72
Baseline Measurements Pre-thyroplasty ...... ... ........................................................ 72 Fundamental Frequency Range ........................................................................... 73 Intensity Range .................................................................................................... 74
............................................................... Stability of Measurements Post-thyroplasty 74 Cornparison of Vocal Function Measurements Pre to Post-thyroplasty ..................... 75
Voice Range Profle ............................................................................................ 75 ......... Fundamental frequency and intensity range pre to pst-thyroplasty 75
......................... Habituai fundamental fiequency pre to pst-thyroplasty 76 .......................................................... Effort Assessrnent Pre to Post-thyroplasty 77
Reading time ...................... .. ................................................................. 77 ......................................................................... Perceptual rating of effort 78
Phonation threshold pressure ........................ .. .... .. ............................. 78 . . . ........................................................................................................ Shidy Limitations 80 .......................................................................................... Sel f-Reported Information 81
............................................................................................................. Conclusions 81
REFERENCES .................... .. ...-.--..--....-...-.-...--.--.-.... .. 83
LIST OF TABLES
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6 .
Table 7.
Table 8.
Table 9.
Table 10.
Table 1 1.
Table 12.
Table 13.
Age, Sex, Duration of S ymptoms and Etiology for Six Subjects
Preoperative Acoustic Data: Habitual Fundamental Frequency in Hertz
(FoH), Jitter and Shimmer in Percent for Six Subjects
Postoperative Acoustic Data: Habitual Fundamental Frequency in Hertz
@OH), Jitter and Shimmer in Percent for Six Subjects
Fundamental Frequency Range in Semitones: Pre and Post-thyroplasty for
Six Subjects
Intensity Range in dB SPL: Pre and Post-thyroplasty for Six Subjects
Modified Voice Range Profle Area: Below (B) and above (A) Habituai
Fundamental Frequency for Six S ubjects
Modified Voice Range Profile - Total Area for Six Subjects
Maximum Phonation Time: Pre and Post-thyroplasty for Six Subjects
Average Phonation Threshold Pressure Values (PTP) in cm Hz0 with
Intensity for Minimum Sustainable Pitch ( F m for Six Subjects
Average Phonation Threshold Pressure Values (PTP) in cm Hz0 with
Intensity for Habitual Pitch (Fm for Six Subjects
Average Phonation Threshold Pressure Values (PTP) in cm Hz0 with
Intensity for Maximum Sustainable Pitch (FoMAX) for Six Subjects
Reading Time (minutes, seconds): Pre and Post-thyroplasty for Six
Subjects
Perceptual Effort Rating: Pre and Post-thyroplasty for Six Subjects
vii
LIST OF FIGURES
Figure 1. Posterior View of Larynx: Diagram of Vagus Nerve
Figure 2. Laryngeal Scoring System for Unilateral Vocal Fold Paralysis.
Figure 3. Voice Range Profile: Total Area Pre and Post-thyroplasty for Six Subjects.
Figure 4. Reading Tirne: Pre and Post-thyroplasty for Six Subjects.
LIST OF APPENDICES
Appendix A.
Appendix B.
Appendix C.
Appendix D.
Appendix E.
Appendix F.
Appendix G.
Appendix H.
Voice Data Collection Sheet
Schematic of Medialkation Thyroplasty
Data CoUection Sheet for Effort Rating
Complete Data for Six Subjects
Examples of Phonation Threshold Pressure
Consent Fonn
Copyright Permission
Terms and Abbreviations
CHAPTER 1
INTRODUCTION
Ovemew
A unilateral vocal fold paralysis (UVFP) due to a recurrent laryngeal nerve lesion
c m cause significant vocal dysfùnction affecthg an individual's ability to effectively
cornmunicate in the workplace and home envimament. Rehabilitaîive measures avaiiahle
include behavioural and/or surgicai treatment if the paralysis does not resolve
spontaneously. More recently, the efficacy of surgical treatrnent has undergone an
Uiçreased amount of scrutiny as speech science advances have provided objective
documentation of vocal fiinction. It is the purpose of this study to examuie the efficacy of
medialisation thyroplasty in a group of UVFP subjects afler a baseline level of vocal
h c t i o n has been established.
Unilateral vocal fold paralysis (UVFP) due to a recurrent nerve dysbct iun is not
a common condition but has been found to occur in appropriately 6.4 per 1000
consecutive patients seen in a general otolaryngology practice (Herrington-Hall, B. L.,
Lee, L., Stemple, J. C., Nierni, K. R & McHone, M. M., 1988). The most common cause
of this condition is neoplasms of the thorax or neck (Dedo, 1970; Tucker, 1980). Other
common etiologies include surgery of the neck and thorax and idiopathic or spontaneous
neuropathy (Parnell & Brandenburg, 1970). The primary effect of UVFP is significant
vocal dyshction.
Many factors contribute to the impaired vocal function in this condition
including.: 1) behavioural compensation 2) respiratory status and 3) arnount of voice use.
Individuals with UVFP usually seek treatment due to the degree of vocal dysfiinction at
the onset of the paralysis. If the paralysis does not spontaneously recover, treatment
options include voice therapy and surgery to the affected vocal fold. Although surgical
treatment has been available for many decades (Isshiki, Okumura & Ishikawa, 1975),
more recent advances in laryngeal surgery have been thought to provide increased
rehabilitation of the UVFP dysphonia (Isshiki et. al., 1975). The present study describes
some of the laryngeal and vocal fimction characteristics of the dysphonia associated with
UVFP. The study also examines the effect of medialisation surgery on these voice
characteristics.
Purpose
The goals of this study were: 1) to objectively quanw specinc parameters of the
dysphonia associated with a chronic compensated unilateral vocal fold paralysis (UVFP)
and 2) to investigate the effects of surgery on these parameters. For the purpose of this
study, unilateral vocal fotd paralysis was defined as a unilateral immobile vocal fold
observable on indirect laryngoscopy with a history compatible with a unilateral recurrent
laryngeal nerve (RLN) paralysis. Before summarising and discussing the relevant
literature of UVFP and its treatment, the pertinent laryngeal anatomy wiil be reviewed, as
well as the natural history of the dysphonia associated with a UVFP.
Laryngeai Anatomy
Laryngeal Muscle Function
The muscles of the larynx can be divided into extrinsic (stemohyoid, thyrohyoid,
sternothyroid, geniohyoid, aryepiglottic and stylohyoid) and intrhsic (thyroarytenoid,
posterior cncoarytenoid, lateral cricoarytenoid, interarytenoid and cricothyroid) muscles.
Of the intriasic muscles, the posterior cricoarytenoid muscle (PCA) carries out the main
abductory (i-e. opening) hc t ion for respiration. Without PCA action, the vocal fold does
not actively abduct (Hiraao, 198 1). In a uniiateral paralysis, there is no airway
compromise since the normal vocal fold provides sufficient abduction to open the glottis
for respiration. The thyroarytenoid (TA) muscle action has two prirnary actions: to adduct
(Le. close or movement in towards the midline) and to alter vocal fold dimensions
(Hirano, 198 1). The thyroarytenoid muscle shortens, rounds and M e n s the main body of
the vocal fold. The fünction of the lateral cricoarytenoid muscle (LCA) h to thin and
elongate the folds as well as to pivot the arytenoid providing a certain amount of
adduction. The interarytenoid muscle (IA) is the sole muscle with bilateral innervation
and consequently retains fiinction in a unilateral paralysis nom the normal RLN.
Contraction of the IA provides some adduction of the bodies of the arytenoids and assists
in closing off the posterior glottis although it is not the main muscle of adduction. In
addition, the IA appears to steady the arytenoid position during phonation.
The primary action of the cncothyroid muscle (CT) is to elongate, thin and tense
or stiffen the vocal fold. Since the innexvation of the CT onginates fkom a separate
branch of the vagus nerve (extemal branch of the superior laryngeal nerve), it maintains
its muscIe tùnction bilaterally with a UVFP (Colton & Casper, 1990; Titze 1994).
in sunmary. diiring phonation, a RLN paralysis d t s in the loss of the ability to
shorten, round and, to a certain degree, sWen the body of the vocal fold. A recurrent
newe paralysis also results in the loss of the active abductory and adductory movement of
the cricoarytenoid joint normally carried out by the PCA and other intrinsic laryngeal
muscles on the affected side.
Innervation of the Laryax
The motor innervation to the larynx is supplied fiom two branches (recurrent
laryngeal and extemal branch of the superior laryngeal nerve) of the tenth cranial nerve
(vagus nerve). The vagus nerve supplies both motor and sensory innervation to the
larynx. The ce11 bodies rest in the nucleus ambiguus in the medulla and the nerve fibres
exit the skull base via the jugular foramen. The superior laryngeal nerve (SLN) carries
af5erent laryngeal sensory information fiom above the vocal folds via the intemal branch.
The external or motor branch of the superior laryngeal nerve emerges at the ievel of the
pharynx and passes antero-inferïorly to innervate the ipsilateral cricothyroid muscle. The
cricothyroid muscle is believed to be a major contributor of vocal fold position when the
recurrent laryngeal nerve is paralysed since it has a separate motor innervation. The
pathway of the recurrent laryngeai nerve is surnmarised in Figure 1. The RLN branches
within the larynx to supply al1 the ipsilateral intrinsic muscles except the cncothyroid
muscle. The RLN also carries sensory aerent information fiom the edge of the vocal
folds and uiferiorly fiom the trachea (Ballenger, 1985; Hirano, 1987).
The iiterahire c o n c e h g W F P ofien does not distinguish between a paralysed
vocal fold due to a recurrent nerve lesion from that of a vagus nerve lesion which results
in a distinct clinical disorder. in a vagal paraiysis, the sensation above and below the
vocal fold is aec ted and all the intrinsic laryngeal muscles includhg the CT muscle are
paraiysed. In addition, the pharyngeal plexus is affecteci redting in pharyngeai
constrictor muscle weakness. The severity of the resulting dysphonia with a vagal paisy is
more extreme given the absence of the cricothyroid and pharyngeal constrictor muscle
activity (see Natural History of üVFP below). The behavioural and structural
compensation in a vagal lesion is not as effective compared to a RLN paralysis (Dedo,
1970). The vocal fold position usually remains lateralised (see Figure 2) in an
intermediate position and the dysphonia does not have the same degree of spontaneous
improvement (Dedo, 1970). The literature regarding treatment evaluation for UVFP often
does not differentiate between a RLN versus a vagal nerve paralysis and consequently the
results must be interpreted cautiously.
Figure 2. Laryngeal Scoring System for Unilateral Vocal Fold Paralysis. Reprinted with permission fiom Hanies, D. G., & Momson, M. (1995). Short-term results of laryngeal fiamework surgery-thyroplasty type 1: A pilot study. The Journal of Otolamp;olop;~, 24.281-287. 1: Most media1 and 5: Most lateral position of the uni%teral paraiysed vocal fold. For example: An intermediate position is scored '3 ' and paramediau position is '2'.
Natural Eistory of Unilateral Vocal Fold Paralysis fmm Recurrent Nerve Paraîysis
The immediate effect on the larynx with an acutely paralysed RLN is a widely
incompetent glottis. During this acute phase, indirect laryngoscopy will demonstrate a
lateralised vocal fold usually in at least an intermediate position (see Figure 2) with a
significant glottic gap during phonation, The dysphonia is usuaily severe with extreme
breathiness to the point of aphonia Dyspnea (shortness of breath) occurs with speaking
due to the enonnoos aitflow during phonation. The acoustic parameters often uiclude en
extremely low fundamentai fiequency (Fo) with a large amount of variability in
periodicity. Acoustic measures commonly used to describe the variability are jitter
(c ycle-to-c ycle variation in fundamental fiequency) and shimmer (cycle-to-cy cle
variation in amplitude).
On stroboscopy (a method of visualising the vocal fol& during the phonatory
cycle using indirect laryngoscopy), there is usually such inegular oscillation of the vocal
folds that the strobe may not accurately detail the phonatory cycle. Visualisation of the
larynx will show the paralysed fold appears to be flaccid and may flutter in an
inconsistent pattern during phonation @kano Br Bless, 1993).
Within weeks, despite a continued paralysis, patients redise significant
improvement in vocal fûnction with better voice quality, increased Loudaess and less
dyspnea with speaking. investigators have indicated that most subjects reach a plateau
with no M e r significant spontaneous improvement between 2 to 4 months (Dedo,
1970). At this point on indirect laryngoscopy, the position of the paralysed vocal fold is
more medial (paramedian) and appears shortened when compared to the unaffected side
marries & Momson, 1995; Hirano & Bless, 1994). The glottic gap is usually reduced in
size (compared to the acute phase) during cornfortable pitch and loudness phonation and
the paralysed fold is rnost often in a pammedian (see Figure 2) position (Dedo, 1970;
Harries & Morrison, 1995).
In the past, researchers have ascribed the paramedian vocal fold position in UVFP
to the adductive action of the intact CT muscles (Grossman, 1897; Wagner, 1890).
Subsequent studies using an animal mode1 of RLN paralysis supported that the
paramedian position of the paralysed vocal fold duing phonation is largely but not
entirely due to CT activity (Arnold, 1955). Later investigators have confirmeci these
frndings @edo, 1970; Konrad & Rattenborg, 1969; Regenborgen, 1989)- Further
evidence to support the CT contribution to the vocal fold position is a cornparison of
vagal paralysis (loss of CT innervation and RLN fiinction) to a RLN paralysis alone. The
position of the vocal fold in a chronic vagal paralysis is typically an intermediate position
between the extreme lateral posture in the acute phase and the paramedian position
typical of a RLN paratysk alone (Dedo, 1970). It has been reporteci that the sectioning of
the CT innervation in bilateral vocal fold paralysis increased the glottic aperture size
(Fischer, 1952; Freedman, 1956).
Woodson, Matthew, Sant'hbrogio, and S a d Ambrogio in 1989, investigated
the position of the glottis at rest and during respiration and have concluded that the
position of the paralysed vocal fold in UVFP is likely multifactorial. Tissue contracture
will cause shortening of the vocal fold that would draw the arytenoid forward and
medially over time and extrinsic laryngeal and pharyngeal muscle activity may assist in
adduction during phonation (Woodson, 1993).
External laryngeal muscles such as the suspensory muscles (stemohyoid,
stylohoid and digastric) and tongue base muscles (genioglossus, geniohyoid and
rnylohoid) also exert an effect on glottal posture (Zenker, 1964). Elevation of the larynx
by the suspensory muscles and tongue base has been shown to increase vocal fold
tension, increase laryngeal resistance and subglottal pressure (Vilkman , Sonninen,
Hurme & Korkko, 1996). Riad and Kotby (1995) performed a study on cadaveric human
larynges simulating a unilateral paralysis and reported that maximum glottal closure was
observed when a combination of extemal and bctioning intrinsic laryngeal muscle
activity was simulated. Elevation of the larynx by the laryngeal suspensoy muscles and
the tongue base plus CT muscle activation demonstrated the most effective closure of the
vocal folds.
Another mechanism available to increase glottal closiue during phonation is the
IA activity since the muscle has bilateral innervation. Electromyographic studies have
confirmed that the IA muscles normally contract during phonation (Dedo, 1970). The
primary action of the IA muscle is to oppose the medial d a c e of the arytenoids and
may be utilised in UVFP patients as a minor compensatory strategy to assist in glottic
closure.
Vibratory Characteristics and Stroboscopy in Uniriteral Vocal Fold Padysis
In the normal mode of vibration, vocal fold apposition by the intrinsic adductors
is followed by a short period of vocal fold closure, followed by an increase in the
subgiottal air pressure beneath the closed folds until the pressure level exceeds the forces
sustaining glottal closure (muscle tension/tissue stiffhess). At this point, the lower edges
of the vocal folds open, followed by the upper edge separating with air escape through
the glottal opening. This will reduce the subglottal pressure and as it falls, the lower
edges are pulled together by negative pressure generated as airflow continues upward but
the airfiow diminishes (Hirano & Bless, 1993; Scherer, 1995). The air pressure just above
the folds falls creating a negative pressure which assists the vocal fold movement in a
medial direction (closure). This sequential oscillation of the vocal folds can be observed
with several methods (i.e., electroglottography and hi&-speed photography) but the best
described and most commonly used is stroboscopy.
Stroboscopy is a method of visualising the vocal fold vibration during indirect
laryngoscopy. The xenon light source is capable of intermittent light exposure
synchronised with the fiuldamental fiequency of vocal fold vibration. The visual
information is a composite of different cycles of vibration at a slightly different time
exposure. This gives the illusion of observing the vocal folds during the sequential phases
of oscillation (Hirano & Bless, 1993). This technique c m be videotaped and digitised for
M e r analysis using image software. There is a large body of iiterahire and texts
describing the normal and pathologie stroboscopie findings (Hirano & Bless, 1993;
Secarz, Berke, Gerratt, Ming & Natividad, 1992). In UVFP, strobscopy will
demonstrate asymmetric oscillation with out-of-phase vibration of the fol& and there
rnay be an asymmetry in the vertical height and vocal fold tension (Isshiki & Ishiwaka,
1976). Propagation of the mucosal wave during normal phonation is dependent on the
sequential closure of the lower edge foilowed by the upper edge during the vibratory
cycle. (Hirano, 1979). Von Leden and Moore (1 960) performed a stroboscopic study in a
canine model under anaesthesia with electrical stimulation of the RLN and SLN.
Simulation of a unilateral RLN paralysis was accomplished by electrical stimulation of
the ipsilateral cricothyroid (CT) and contralateral CT muscle and RLN. These tesearchers
observed that under these conditions, a posterior glottic chink was present with
significant air leak during phonation. Under forced airflow vibration of the vocal fol& in
this model, three characteristics were observed. First, the upper edge of the paraiysed fold
opened fkst during phonation @hase lead) compared to the nomial side, second, the
lower edge of the fold lateralised M e r than the normal side (larger amplitude), and
diird, the normal fold was shown to have reduced amplitude and mucosal wave.
Studies in humans g e n e d y agree with the animal model of stroboscopic
abnorrnalities. Schoenharl in 1960 (in Von Leden & Moore, 1960), reported that 55/62
patients with unilateral laryngeal paralysis dernonstrated loss of mucosal wave
propagation on the paralysed side when observed with stroboscopy. Aiso in 1960, Von
Leden & Moore used high speed photography and dernonstrated that in two subjects with
chronic RLN paralysis, the vocal folds had the same basic fùndamental fiequency but
their vibration was out of phase with the healthy fold laterdishg first during initiation of
phonation. The vibratory pattern was observed to have a variable phase asymmetry
during phonation.
Hirano & Bless (1 993) reported phase asymmetry and diminished amplitude on
the paralysed side until the vocalis is Mly atrophied at more than two years after a
WVFP. At this point the fold may become thin and flaccid with excessive amplitude.
Theoretical Effects of Unilateral Vocal Fold Paralysu on Fundamena Frequency
and intensity
Physiologic Control of Pundamental Frequency
Control of fundamental fiequency is primarily a hinction of the vocal fold length,
tissue tension or Stïfkess and subglottal pressure. Other important factors are
thyroarytenoid muscle contraction and the amplitude of the folds during the phonatory
cycle. (Scherer, 1991). Although there are several more complex formulas under
development, the following formula (Scherer, 199 1) which models a stretched, vibrating
string describes the essential contributhg factors.
Formula 1-
Fo is fiindamental f?equency
L is length of vocal folds
T is mean force per unit cross-sectional area (stiffhess)
P is the tissue density (nomally constant)
S tiffness (Tension)
During normal phonation, the main determinant of Fo is tension or stifniess of the
surface cover of the vocal fold, which is mostly influenced by the cricothyroid muscles.
Since both the CT muscles are active in UVFP, tension can be increased by CT activation
as the CT elongates the folds. This h a two effects on the vocal folds. The increase in
length (L) tends to decrease Fo but the increase in s t f i e s s or T would have the opposite
ef5ect of increasing Fo. Increasing s t f iess Cr) during CT activation dominates with the
overall result of raising Fo. As previously discussed, the cricothyroid muscle has also
been shown to adduct the fol& to a minor degree when activated (WOOdSOn e t ai., 1993).
Maximising the CT activity during phonation by subjects with UVFP is a iikely
compensatory mechanism and would theoreticaiiy result in an elevated habituai Fo
(Trapp, Berke, Bell, Hanson & Ward, 1988). Hirano (198 1) documented that the subjects
will also have an elevated minimum sustainable Fo-
One of the areas of interest in the current shidy was a postulateci reduction in
fundamentai frequency range in subjects with a compensated UVFP. The ratior.de for a
reduced Fo range is based on the physiological elements that control frequency and is
discussed below.
Thyroarytenoid Muscle Contribution
The main tissue mass of the vocal fold is made up of the TA. Although the total
mass of the vocal fold is constant, the cross sectional area can be altered by changes in
TA dimensions. In the normal larynx, as the mass of the vibrating portion of the fold is
increased, the cross-sectional area is also increased, and thus, the force per unit area
would decrease, effectively reducing Fo. This task is normaily performed by TA
activation, which shortens the folds thereby reducing tissue st8fhess. in UVFP, where the
paralysed fold is lacking thyroarytenoid muscle fwiction and is in a paramedian position,
a reduced cross sectional area of the fold would be contributing to the vibrating portion
for the following reasons. Fust, the paralysed thyroarytenoid muscle is unable to contract
and increase relative cross-sectionai area. Second, the TA wiii be reduced in mass due to
loss of muscle bulk after paralysis, which also reduces muscle tissue stifhess, and third,
the paramedian position of the fold would reduce the amount of the fold available to
participate in vibration.
Length
As discussed above, CT activation increases length but also increases d a c e
tension with the cumulative effect of increasing the fiindamental fiequency. With a
UVFP, active shortening of the folds would be Iimited since the intrinsic muscles are
p d y s e d . Passive shortening of the paralysed fold would occur with CT relaxation.
Woodson (1993) has suggested that tissue contracture may also shorten the paralysed
fold. The effective vibrating length of the fold would also be shortened by the presence of
glottic gap where only a segment of the folds are in close enough proximity to vibrate
( < l m ) (Titze, 1994). Since the abiiity to actively shorten the fold is limited in UVFP
due ro TA paralysis, this theoreticaily would in part account for a reduction in the Fo
range at the lower end in U V F P subjects.
Subglottic Air Pressure
Subglottic pressure contributes to fûndamental fiequency control as a mechanical
influence but is not one of the major detenninants of Fo. As subglottic pressure is
increased, the maximum laterai excursion during phonation (amplitude) of the fold also
increases. The increase in amplitude wodd also raise stiffness of the vocal folds. This
effort on stifiess causing a rise in Fo is more prominent at low pitch when the folds are
more relaxed. If the fol& are already stiff (at high Fo or in hyperfiinctional states), there
is little effect on pitch by increasing subglottic pressure (Scherer, 1991).
In W P , the presence of a glottic gap during phonation may limit the ability of
the larynx to raise subglottic pressure, which normally occurs with increasing Fo or
intensity level. In theory, the limitations of subglottic pressure would contribute to a
reduction in Fo range in UVFP subjects.
Behavioural Mechanisms
A hyperfiinctional appearance to the glottis duriag habituai pitch and loudness has
been observed in UVFP with increased supraglottic activity observed during stroboscopy
(Hirano, 1 993 ; Khidr, Ramos, Bless & Heisey, 1 997). ExtRasic and suspensory laryngeal
muscle activation (see page 8) are behavioural cornpensatory mechanisms which hcrease
stifiess in the vocal folds during phonation by increasing laryngeal height and
compression. Both CT activation and supraglottic hyperfiinction increase glottic closure
(Riad & Kotby, 1995; Vilkman, Sonninen, Hurme & Korkko, 1996) and are
compensatory manoeuvres available in UVFP. Not al1 subjects WU utilise these
manoeuvres to the sarne degree. Using perceptual cues, subjects with a change in vocal
function will attempt to improve their vocal quafïty. Such adaptation wili likely depend
on the individual's subjective target voice, vocal demand, and ability of the compensatory
structures to participate in the adaptation process.
Fundamental Frequency Range
A reduction in Fo range is an expected result of W F P with less capacity to
manipulate the parameters of Fo control (stifhess, vibrating length, mass and subglottic
pressure). One study (Sawashimq Totuska, Kobayashi & Hirose, 1 968) was reported by
Hirano in 198 1 and observed that al1 15 subjects investigated with a vocal fold paralysis
had a reduced maximum sustainable hdarnental fiequency (FoMAX). However, 1 1 of
15 subjects also had an elevated minimum sustainable fiindamental frequency (FoMIN)
while the remaining four subjects were slightly below normal control values. The mean
speaking bdamental fiequency was found to be above normal in 91 15 and below normal
in 6/15. Despite spontaneous improvement in vocal hc t ion &er the onset of a UVFP,
compensated subjects appear to have continued reductioas in Fo range. The first
hypothesis of this study was to investigate a fairly uniform sample of UVFP subjects to
deterrnine if the Fo range is below published normal values.
In tensity
The main determînant of intensity is subglottic pressure (Scherer, 1991). In order
to increase subglottic pressure, the lungs must force an increased amount of air pressure
under the adducted vocal folds, which have a certain degree of resistance. The air
pressure must overcome the glottic resistance to initiate phonation and the degree of
stiffhess in the folds is a function of intrinsic and extrinsic muscle activity. In UVFP, one
foid is relatively lax compared to the normal side. During attempts to increase intensity,
there is a tendency for the folds to permit air escape, limiting the capacity to raise
subglottic pressure and therefore loudness. Conversely, some authors have reported that
subglonal pressure during normal pitch and loudness phonation has been elevated in
recurrent nerve paralysis (Hirano, 198 1) which was attributed to supraglottic
hyperfùnction secondary to behavioural compensation.
Another factor affecting intensity is the rate of airfîow cutsff during the
phonatory cycle- During glottic closure, a negative pressure is created within and just
above the glottis as less air passes up fiom below due to the rarefaction of the air
particles. The more rapidly the folds shut during the closing phase of the phonatory cycle,
the higher the intensity (Gauffin & Sundberg, 1989). Since the paralysed vocal fold has
less mass and tissue stiffhess resuiting in asymmetric glottic closure during phonation
(see Stroboscopy in UVFP), theoreticdy, the closing phase speed wodd be variable and
likely reduced. The dynamic or intensity range capability of UVFP subjects should be
reduced based on restricted subglottic air pressure levels and phonatory cycle asymmetry.
Given the vocal fiuiction !imitations with an expected reduced fiuidarnental
fiequency and intensity range with a compensated, chronic UVFP, effective treatment is
desirable. Such treatment has two main options: behavioural and surgical.
Treatment of Unilaterai Vocal Fold Paralysis
Behavioural and surgical treatment options are available for the dysphonia
associated with UVFP. Behavioural therapy has been directed at training compensatory
strategies. Other counter productive compensation mechanisms (i.e. excessive ventricdar
vocal fold phonation), that the patient may have developed can be identified and treated
In some cases, pitch modification training has been done (Benninger, C d e y , Ford,
Gould, Hanson, Ossoff & Sataloff, 1994) as well as increasing respiratory support, voice
exercises and vocal hygiene (Colton & Casper, 1990). Behaviourd training may, in some
cases, improve the vocal function such that the patients do not seek m e r intervention.
Some individuais find that although there is a significant change in the voice, their
particular vocal demands may be modest enough that no treatment is desired. However,
many patients continue to complain of altered vocal quaiity, voice fatigue and reduced
intensity. Since these symptoms persist despite spontaneous and behavioural
modifications, clinicians have sought surgical means to improve vocal function in
patients with UVFP.
Surgicd treatment for a UVFP condition has been available for decades. Three
main forms of surgicai intervention exist; augmentation, medialisation thyroplasty and
arytenoid adduction. Arytenoid adduction is a surgical technique, which involves the
repositioning of the arytenoid by rotating it medially thereby irnproving glottic closure
but uiis procedure has not been used extensively in Canada and will not be discussed.
Augmentation of the Paralysed Fold
The earliest form of surgical treatment involves augmenthg the paralysed fold
with an injectable matenal such as Teflon, coilagen or fat. The treatment was initiated in
1 9 1 1 using para& (Bruenings, 19 1 1 ). Augmenting the fold with either indirect
laryngoscopy or direct vision under a general or local anaesthetic has several advantages.
It ailows specific site augmentation, minimal general or local anaesthetic is required and
is a relatively easy technique. Specific tissue loss or atrophy can be addressed with
augmentation by injection. The material most often used has been ~eflon~@ol~tef).
Unfortunately, one of the liiniting factors is a tendency for a grandomatous inflatnmatory
reaction to occur months or years after ~ e f l o n ~ injection and granuloma formation can
cause severe dysphonia ~ e f l o n ~ cm be difficult to mold into the desired contour since it
must be placed deep in the thyroarytenoid muscle and it is extremely difficult to remove
once it solidifies within the TA. The vocal fold has been reported to stiffen and lose
vibratory characteristics after ~ e f l o n ~ injection (Watterson, McFarlane, & Menicucci,
1990). In one report which cornpared ~ e f l o n ~ and thyroplasty, sübjects who had
undergone thyroplasty were found to have increased glottic clonire, preserved mucosal
wave, irnproved perceptual qualities and laryngeal resistance (Dl Antonio, Wigley, &
Zirnmerman, 1995) compared to the injection method. Nonetheless, ~ e f l o n ~ injection has
been the mainstay of voice rehabilitation after unilateral paralysis since the 1960's. Fat
injection has been utilised more recently for vocal fold augmentation with autologous
tissue (Brandenburg, Berke, & Koschkee, 1992: Mikaelian, Lowry, & Sataloff, 199 1 ;
Mikus, Koufinan, & Kirkpatxick, 1995). Concems about the amount and longevity of the
fat implanted as a fiee tissue transfer has limited its widespread use. Collagen injection
has similar augmentative capabilities also with some loss of material over tirne. The
collagen currentiy available is bovine and a proportion of patients will sustain an allergic
reaction restricting its application. Because of the Limitations and potential adverse effects
after vocal fold augmentation by injection, other surgical methods primarily
mediakation thyroplasty, were developed.
Medialisation Thyro plasty
Isshiki in 1975 described medialisation thyroplasty where the goal of the
procedure is to medialise (move towards the midline) the paralysed fold by placiog a
solid material undemeath the vocal fold fiom outside the larynx. This modification of
previous work by various surgeons in the earlier part of this century uses an extemal
approach to the thyroid cartilage of the larynx. Briefly, a window or opening is made in
the thyroid cartilage over the afTected paralysed vocal fold. A shaped piece of silasticR
block is placed under the inner perichondrium with the effect of pushing the vocal fold
towards the midline (see Appendix B). Local anaesthetic and mild sedation is used and
the patients can phonate during the procedure. Advantages of medialisation thyroplasty
include: 1) variable degree of medial positionhg by altering the block shape/size in
response to phonation intraoperatively and 2) the cover and fiee edge of the fold is not
affected and 3) the procedure is well tolerated under local anaesthetic. The silasticR
implant can be modified later or removed completely if, for example, the silasticR block
requires modification in size/shape or the UVFP recovers. Theoretically, the
improvement in vocal function is based on a more mediai position of the vocal fold edge
therefore reducing or eliminating glottal gap without interfering with the vibratory
properties of the paralysed fold.
Many reports describing fiirther technical modifications of Isshiki's originai
description have appeared in the last 20 years. Although most reports were procedure
oriented with little evaluation of vocal fûnction (Hof i an & McCulloch, 1996; Koufman,
1986; Tucker, Wanarnaker, Trott & Hicks, 1993) some recent studies have focused on the
effect of thyroplasty on vocal fuaction (Gray, Barkmeier, Jones, Titze & Druker, 1992;
LaBlance & Maves, 1992; Leder & Sasaki, 1994). Since UVFP is an uncornmon
condition, most reports do not stratifi the subject population as to the etiology of the
W P condition. Results fiom an unstratified group of mixed etiology, undetermined
duration of paralysis and respiratory function will be dficuit to extrapolate to the subject
with a compensated UVFP due to a RLN pardysis. Another consideration is that early
surgical intervention may show apparent improvement in vocal fiinction that might have
occurred spontaneously. A comprehensive but not exhaustive review of the literature
conceming the objective evaluation of vocal function in UVFP is discussed below. The
effects of medialisation thyroplasty upon the major parameters controliing Fo and
intensity are also reviewed.
Theoretical Effeet of Thyroplasty on Fundamenbl Frequemy and Intensity
Medialisation thyroplasty, by placement of a Silastic block under the paralysed
foId and pushing the vocal fold toward the midine, should have several direct and
indirect effects on vocal fiinction. First, the most obvious direct effect is a reduction or
closure of the glottic gap duriog phonation. A reduced amount of aimow during
phonation should occur with the ability to generate larger subglottic pressure levels and
laryngeal resistance. Since subglottic pressure level is the main determinant of intensity,
thyroplasty should increase intensity range. An indirect effect of improved glottic closure
may be that less effort is required to omet and sustain phonation. As previously
mentioned above, laryngeal resistance was highest in LTVFP when al1 available
fimctioning laryngeal and extrinsic muscles were activated (Riad & Kotby 1995;
Vilkman, Sonninen, Hume Br Korkko, 1996). This type of behavioural compensation
may no longer be required after thyroplasty.
The second direct eEect afler thyroplasty is the increase in mass of the paralysed
vocal fold. This relative increase in mass of the paralysed fold without TA activity would,
in theory, d o w for an expansion of the Fo range at the lower end.
The third direct effect of medialisation surgery is a relative increase in the
vibrating length of the folds. The reduced or closed glottic gap after thyroplasty allows a
longer segment of the vocal fold edges to approximate and effectively increases the
length of the folds available to participate in the vibratory cycle. This potential increase
in vibrating length would, in theory, permit an increase in Fo range by virtue of both the
increase in length and increased capacity to alter surface tension. The adductory action of
the cricothyroid muscle may not be required to the same degree since the folds would
have Vnproved adduction with the silasticR block in place. With less CT activity, s d a c e
tension can be reduced, expanding the Fo range.
As a result of thyroplasty, there would be an increase in intraglottai pressure
(pressure between the approximated vocal fold edges) during the vibratory cycle with iess
air escape. The amplitude or lateral excursion of the fol& during phonation would
increase with the improved closure and potentialiy a longer segment of medial fold edge
approximation. These direct effects would contribute to Fo in a variable manner
depending on the subjects' vocal task and other intrinsic muscle activation, most
irnportantly, CT activation. However, improving glottic closure should result in improved
capacity to raise subglottic pressure and improve vibratory symmetry. An inmease in
intensity range pst-thyroplasty is anticipated. Overaii, thyroplasty should increase Fo and
intensity range capability due to the direct effects on the stiffness, length, mass and
subglottic pressure as weli as indiredy Secting the behavioural mecfhanisms in use.
Literature Review of Vocal Effects After Medialisrition Thyroplasty
The type of vocal function parameters that have been utilised to evaluate the
effectiveness of thyroplasty for UVFP include stroboscopic descriptive measures,
perceptual analy sis, acoustic analy sis of iso lated vowels, and aerodynamic measures
(maximum phonation time). Overall, the literature indicates that although these
parameters tend to improve, vocal parameters do not necessarily normalise (LaBlance &
Maves, 1 992; Leder & Sasaki, 1994).
Stroboscopy Evaluation
Stroboscopy has been utilised in studies examining the effect of medialisation
thyroplasty on the vibratory characteristic in subjects with a W P . Since medialisation
surgery is designed to alter the position of the paralysed fold, stroboscopic evaluation pre
and postsurgery is an obvious measure of effectiveness. During habitual pitch and
loudness, the position of the paralysed fold and glottal gap area can be measured
accurately. The details of the oscillatory pattern during phonation can also be assessed.
Abnomalities evident in either the normal or paraiysed fold such as phase asymmetry,
amplitude differences and mucosal wave magnitude can be observed. Patterns of
vibration depend largely on the presence and size of glottk gap if the vocal fold tissue
has not otherwise been damaged (Isshiki, 1977). These authors noted that changes in
glottal area, subglottal pressure, and stiffness of the fol& would cause the vibration to
shift between three basic patterns: 1 ) minimal gap with relatively preserved symmetry of
vibration, 2) moderate sized gap with more irreguiar vibration and 3) a wide glottic gap
without any closure during phonation. (Isshüri, 1977). Increasing glottal gap closure in
computer simulation models, in vitro experiments and human studies has been shown to
alter the vibratory pattern of the vocal fol& @ielarnowicz, Berke, Watson, & Gerratt,
1994; Isshiki, Tanabe, Ishizaka, & Broad, 1977; Smith, Berke, & Kreiman, 1992; Tanabe,
lsshiki & Kitajima, 1972) and has been found to correlate with perceptual features of
dysphonia
Evidence of behavioinal compensation such as increased supraglottic activity in
the horizontal or anterior-posterior plane can be evaluated during a stroboscopic
examination. Excessive ventricular vocal fold activity can be observed and may even
obscure the underlying paralysed hue fold during phonation. Increased supraglottic
activity during phonation is a non-specifk sign of increased effort in glottal dysfiuiction
(Hirano, 1993; Khidr, Ramos, Bless, & Heisey, 1997).
The effects of medialisation surgery upon the many stroboscopic parameters
discussed have been partly addressed in the literature. Mucosai wave in the paralysed fold
improved in 911 2 patients in a study fiom the Mayo Clinic (Thompson, Maragos &
Edwards, 1995) d e r thyroplasty. In this study, phase asymmetry was observed in 9/12
pnor to sugery and was still present in 6/12 post-thyroplasty. Although this seems to
indicate an improvement in vibratory symmetry &er thyroplasty, both RLN and vagal
paralysis subjects were Uicluded and two different surgical procedures were used. One
report on 18 patients with a RLN lesion pre and post-thyroplasty (Omori, Slavit, Kacker
& B laugmd, 1 W6), performed stroboscopy during a sustained vowei at habituai pitch
and loudness. Analysis of the stroboscopic data was done to evduate the relative glottal
gap size (in relationship to the normal fold length) and showed a significant reduction
post-thyroplasty. The reduction of specific acoustic parameters (percent jitter, percent
shimmer and harmonic to noise ratio among others) correlated with the relative glottai
gap area. The acoustic parameters most frequently reported in the literature to describe
vocal function are fundamental fiequency (Fo), percent jitter, percent shimmer, and
hannonic to noise ratio (HNR) (Baken, 1 987) and are discussed in more detail below.
Acoustic Parameters
Fundamental fiequency.
Fundamentai fkquency (Fo) of isolated vowels is readily assesseci and a
commonly reported parameter in vocal dysfiinction. In UVFP, the duration fkom onset of
the paralysis wilt influence this parameter tremendously. Any improvement in glottal
closure will have the effect of increasing Fo in the penod immediately foliowing onset of
the vocal fold paralysis.
Hanson and Berke (1988) published a report, which focused primanly on
eiectroglottography in laryngeal paralysis, and the authors did iden* the etiology and
duration of the vocal paralysis. Twelve male subjects with a unilateral RLN paralysis for
more than 12 months were included in the study and were found to have a significantly
elevated Fo (isolated vowel at habitual pitch and loudness) than a control group (Hanson
& Berke, 1988). This finding supports one of the theoretical effects of UVFP on Fo
control. By elevated Fo with cricothyroid activity (CT), glottal tension and closure are
increased. As a compensatory mechanism, glottic tension is primarily increased with CT
activity .
After thyroplasty for UVFP, habituai Fo has been reported to increase, decrease or
remain unchanged (Sasaki, Leder, Petcu, & Freidman, 1990). Sasaki et. al., (1990)
observed an increase in Fo level post-thyroplasty in a mostly female study group. In a
publication by Lundy and Casiano (1995), Fo was reduced after thyroplasty in subjects
with a 'compensatory falsetto' due to a UVFP. These same authors had reviewed al1
patients seen in a large voice clinic with an abnormally elevated Fo and found that ten
percent were attributed to a unilateral paralysis. However, in a separate report (Lu,
Casiano, Lundy & Xue, 1996) obseMng Fo fiom isolated vowels (habitual pitch and
loudness) the subjects were found to be within the normal range prior to surgery and did
not significantly change after thyroplasty.
Thus, the literature does reveal that in some subjects with UVFP for at least six
months, habitual Fo may be elevated. Other studies have reported within nomal or
reduced Fo levels. The coaûicting evidence in the Literature regarding habitual Fo
evaluation in UVFP where both an elevated and reduced Fo has been reported may be a
iack of stratification for etiology and duration of the paralysis in the subjects. Other
factors may be the timing of surgical intervention and the variability of individual
behavioural compensation.
Perturbation measurements.
Other common acousùc parameters reported as measws of dysphonia with
UVFP are jitter (cycle-to-cycle vaiability in fùndamental fiequency), shMmer (cycle-to-
cycle variability in amplitude) and hamionic-to-noise ratio. Percent jitter and shimmer are
referred to the perturbation measurements of an acoustic signal. Overail, improvements
(reduction) in the percent jitter and shimmer wen reported pst-thyroplasty (Hames &
Morrison, 1995; LaBlance & Maves, 1992; Lu & Casiano, 1996; Omori et. al., 1996;
Slavit & Maragos, 1994) but were not consistently abnormal prior to thyroplasty.
Perturbation measures have been fomd to continue to irnprove for over a year foliowing
thyroplasty (Kamell MP et. al., ASHA Meeting 1997).
There likely is an improvement in acoustic measures in a subject with
compensated UVFP after thyroplasty, over and above the spontaneous improvement that
occurs, but it is not clearly evident in the Iiteratwe. There is a tendency to combine
different etiologies and duration of paraiysis in the same study group and overall, a high
degree of individual variability has been observed (Gray, Barkmeier, Jones, Titze &
Drucker, 1992)
Fundamental frequency range.
Two reports evalriirted fùndamental fiequency range in UVFP. The normal value
for Fo range is dependent in part on age and sex. Several authors have documented that
the normal fundamental fiequency range for adults (20-60 years) is 36 semitones (ST)
(Coleman, Mabis, & Hinson, 1977; Hirano & Bless, 1993). There is a wide variability of
normal and Coleman et, al., (1977) recommend that if the fiindamental fiequency range is
below 20 ST, it should be considered abnormal.
The h t study concerning UVFP subjects reported that fundamental tiequency
range increased fiom a mean of 12 semitones (range 7 to 20 ST) prior to surgery to a
mean of 23 semitones (range 16 to 32 ST) one month post-thyroplasty (LaBlance, 1992).
The study grouped six RLN paralysis subjects with two vagal paralysis subjects and the
duration of the voice disorder was fiom 9 to 38 months. The second study (Gray et, al.,
1992) was done on a group of pst-thyroplasty subjects with UVFP of unreported
etiology and compared to a normal control group with no presurgical baseline data. In
this study, 15 subjects were evaluated and demollstrated a mean Fo range of 16 ST
compared to the normal value of 35 ST. Al1 subjects in these two studies reported a
subjective decrease in pitch range prior to surgery and in the first study, the Fo range
increased by almost 100%. Despite the improvement after thyroplasty, most subjects in
these two studies had an abnomally reduced Fo range (<20 ST).
Intensity.
Intensity capability in UVFP has not been examined in great detail but some
evidence suggests that maximum intensity is reduced compared to normal values.
Although multiple factors contribute to increase intensity normaiiy, increasing glottal
resistance and subglottal pressure are the major components (Scherer, 199 1 ; Titze, 1992).
Post-thyroplasty, maximum intensity (uncontroiled for Fo) bas been observed to increase
although the maximum intensity level was not invariably abnormal prior to surgery.
(Hamies & Momson, 1 995; Sasaki et. al., 1 990; Slavit & Mamgos, 1 994). In one study of
15 post-thyroplasty subjects (Gray et. al., L992), observed a mean intensity range of 22dB
compared to a normal value of at teast 40dB.
Voice Range Profile.
Voice range profile (VRP) is one method of descnbing au individual's vocal
maximai capacity combining Fo and intensity. The usual method of determining the VRP
is to fmt establish the fiindamental Fequency range, then the Fo range is divided up into
increments i.e., ten percentile segments. The maximum and minimum intensity is then
established at each Fo increment. The usual display of this data is in graphic form with Fo
on the x-axis in a logarithmic scale (either semitones or ten percentile increments) and the
maximum and minimum intensity (in dB) on the y-axis for each fiequency tested. A
reduction of the voice range profile (VRP) is a cornmon abnomality in many laryngeal
disorders (Titze, 1 992). One study, which evaluated a VRP in pst-thyroplasty, subjects
(Gray e t al., 1992) showed data for only four of the fifteen subjects. The best result
demonstrated that the VRP was still abnormal with reduced Fo and intensity values and
unfortuuately, no presurgid data were reported. Theoretically, VRP should increase
post-thyroplasty since the two parameters, which are combhed to generate the data (Fo
and intensity) should improve as discussed above.
Aerodynamics
An incompetent glottis with hadequate closure will demonstrate excessive
air£iow during phonation. The most comrnon aerodynamic parameter used to quanti@
glottic competency is maximum phonation time (MPT) or the length of time in seconds
that a vowel c m be sustained. This measure is not usually controlled for pitch or
loudness. Maximum phonation time is abnormal in UVFP during the acute phase but is
not always abnormal in the compensated stage of vocal fold paralysis (Leder & Sasaki,
1994; Lu et. al., 1996; Netseil, Lotz & Shaughnessy, 1984). in most reports, MPT has
been shown to significantly krease pst-thyroplasty and remain consistently improved
up to the three months postsurgery (Harries & Sasaki, 1990; Karnell, 1997; Lu &
Casiano, 1996; LaBlance et. al., 1992). Mean airfiow during a sustained vowel also gives
an indication of the amount of air leak during phonation and has similarly been shown to
improve (reduce) pst-thyroplasty (Harries & Morrison, 1995; Lu et. ai., 1996; Netsell et.
ai., 1984).
Intraoral air pressure during a voiceless bilabial consonant can be used to estimate
subglottic pressure and is a well-accepted method of estimating subglottic air pressure
during phonation (Smitheran & Hixon, 198 1). With subglottic air pressure and aïr£low
data, laryngeal ainvay resistance &AR) @ressure/airtlow) can be calculated. Three
subjects with UVFP were evaluated with repeated syllables of a bilabial consonant and
vowel (Le., /pi/pi/pi/) and were observed with increased airflow (Netsell et. al., 1984).
However the same study found both normal and elevated subglottic air pressure levels
(Netsell et. al., 1984).
There are few data available on the effect of thyroplasty upon subglottic au
pressure or LAR. The logical effect of thyroplasty on airflow during phonation would be
to cause a reduction in airflow during phonation that given the paralysed fold was
medialised, resulted in more effective glottic closure and improved laryngeal resistance.
The effect of thyroplasty upon subglottal pressure is difncult to predict. If the
individual with UVFP has a suffïciently leaky glottis during phonation, the subgiottic air
pressure may be lower than anticipated with increased aidow. As a result of the
thyroplasty, the glottis is rendered more competent during adduction with less airflow,
and subglottal pressure may be normal pst-thyroplasty. Other factors must be considered
such as the fimdamental fiequency and intensity level tested. At a low Fo, the vocal folds
will have less sti£kess and both the airflow rate and glottic gap size may be increased
compared to a higher Fo within the same subject At a higher Fo, the folds wili likely have
more stifiess due to the intact cricothyroid activity and other behavioural manoeuvres
may assist in increasing overall laryngeal resistance- In this condition of increased
stiffiess with supraglottic hyperfunction, subglottic air pressure may be normal or even
elevated In this circumstance, subglottic air pressure may decrease after thyroplasty fiom
an elevated level.
Another aerodynamic measure has also k e n utilised primarily in normal subjects
to evaluate the ease with which a subject produces phonation. This measure is tenned the
phonation threshold pressure and is defined as the minimum subglottd pressure required
to initiate vocal fold oscillation. Although thîs is an aerodynamic measure, the clinical
usefuloess of this parameter is to evaluate the ease with which a subject can produce
voice (see below). Phonation threshold pressure has not been examined in UVFP or in
subjects after thyroplasty. PTP values are greatly affected by the Fo tested. PTP levels are
raised by increased Fo, increased stifhess, decreased thickness of the vocal fol& and an
increase in mucosal wave velocity (Verdolini et- al., 1990).
Fatigue or tiring of the voice, is a common but non-specific cornplaint with many
laryngeal disorders. Symptoms such as throat discornfort, neck tightness, increased effort
during speech are common in a chronic UVFP (Colton & Casper, 1990), but are non-
specific. Reports investigating vocal fatigue are few. One study (Stemple, Stanley & Lee,
1995) performed objective measurements of voice production in experirnentally induced
laryngeal fatigue evaluating ten normal speakers with two hours of continuous reading at
a controlled intensity (75-80dB). Acoustic parameters (Fo. fiequency range and jitter) and
aerodynamic masures (MPT, airflow) showed no significant changes except that
subjects experienced a signifïcant increase in Fo during reading. This result was similar
to a previous report by (Gelfer, Andrews, & Schmidt, 1991) which also showed an
increase in Fo d e r a one-hour reading task. This was attributed to thparytenoid muscle
fatiguelweakness, reducing the ability of the vocal fold to shorten and d u c e tension in
the vocal fold surface. Videostroboscopic aoalysis afier the one hour reading session
showed the development of a smaif anterior glottic chink in 6/10 subjects. It appears that
normal speakers can easily complete at least two hours of reading at 75-80 dB intensity
level with few alterations in vocal function. In UVFP, no data are available on prolonged
connected speech tasks. The clinical profile woutd suggest that subjects would experience
fatigue far earlier with limitation on prolonged reading.
Effort during speech is a difficult parameter to quanti* objectively. One recently
developed method is to evaiuate the phonation threshold pressure (PTP), defked, as the
subglottal pressure required to onset phonation at the lowest possible intensity. When
trained singers were instructed to increase their effort, PTP leveb were shown to increase
(Gramming, 1 988)- Normal subjects were investigated and found to have mean PTP
values which rise with increasing Fo- For example, at a high Fo ( 8 0 ~ percentile of Fo
range), mean PTP was 6.73 cm &O (Verdolini-Marston, Titze, & Druker, 1990). The
same study showed at low Fo ( 2 0 ~ percentile Fo range) testing, the PTP vaiue was 3.52
cm HzO, very similar to the FoH value of 3.34 cm Hz0 (VerdoLini-Marston, et. al., 1990).
As part of behavioural compensation with a unilateral paraiysis, subjects may increase
overail effort (intrinsic/external laryngeal muscular activity) to initiate and sustain
phonation. Since thyroplasty should improve glottal closure, subjects may demonstrate a
reduction in the effort required to initiate oscillation and a reduction in PTP level rnay be
detectable. Stroboscopie evidence of effort has k e n described in relation to the increase
in supraglottic activity in either the anterior-posterior or lateral-medial direction. (Hirano
& Bless, 1993) The appearance of false vocal fold, aryepiglottic and tongue base activity
duruig sustained vowel phonation can be evaluated by expenenced, trained observers
with a rating scale. (Ramos Pizarro, 1998).
One report on vocal fatigue (Stone & Sharf, 1973) observed perceptually
detectable fatigue far earlier in normal subjects who were asked to speak at an elevated
fundamental fiequency level(50% and 80% of their total Fo range) compared to their
habihial Fo. These data may shed some Light as to why UVFP subjects experience fatigue
since similar behavioilral mechanisms would be in effect during high frequency speech as
in UVFP phonation,
Perceptual Characteristics
Perceptual evaluation has commonly been used to assess vocal quaiity but
infkequently used to assess effort. LaBlaace and Maves (1 992) performed a perceptuai
evaluation of eight UVFP subjects reading a one-minute monologue. AU subjects were
obsemed to have diplophonia, hoarseness and breathiness. Two of eight subjects were
found to have vocal strain. After thyroplasty, ail eight subjects were reported to have no
abnormal breathiness but hoarseness was still judged to be present in six of eight
subjects. Gray et. al., (1992) observed that 15 pst-thyroplasty were still found to have
increased harshness, strain and breathiness. Reduced breatbiness has been observed after
thyroplasty compared to the presurgical state (Lu et. al., 19%)
Effort has been utilised as a perceptuai characteristic in a study comparing voice
results between two partial laryngectomy surgical procedures (Doyle, Leeper, Houghton-
Jones, Hemerman, & Martin, 1996). Effort was defined as the amount of effort the
listener thought was required for the speaker to produce speech and rated on an equal
appearing, nine-point scde. To date, similar applications have not been used to evaluate
UVFP subjects-
Although it has been reported a subjective complaint (Gray et. al., 1992), effort or
vocal fatigue in subjects with a UVFP has not been evaluated objectively. Since
subjectively, vocal fatigue and increased effort during speech are common symptoms
with UVFP, if medialisation thyroplasty is an effective rehabilitative treatment, it should
be possible to observe a reduction in effort as a percephial feature.
The literature is helpful in objectively describing some of the voice abnonnalities
associated with a UVFP. It seems clear that acoustic parameters are ofien but not always
abnormal with fiindamental fkequency reported a b n o d y elevated or reduced.
Perturbation measures are genedly elevated compared to published normal values.
Aerodynamic measurements have provided convincing data that UVFP subjects have an
abnomially increased airflow during phonation as a result of incomplete glottic closure.
M e r medialisation thyroplasty, aerodynamic measures such as mean airflow and MPT
have shown significant improvements. Stroboscopie evaluations have documented
improvement in certain characteristics of the oscillatory cycle after thyroplasty but do not
completely normalise.
The Literature supports thyropiasty as an effective rehabilitative masure for some
of the symptoms associated with a UVFP dysphonia. It is not clear whether some of the
improvements documented in the literature attributed to thpplasty, are over and above
the spontaneous compensation foilowing the omet of a UVFP. Other potential benefits
fiom rnedialisation surgery such as a reduction in vocal effort have not been investigated
objectively. The present study was designed to evaluate a relatively homogenous group
of UVFP subjects and to document that their dysphonia was stabie over a period of tirne
before medialisation surgery. This wodd minimise spontaneous improvement as a
confounding factor when evaluating the effect of medialisation surgery. The subjects
would be re-evaluated for a penod of time afler thyroplasty to observe the effect of the
treatrnent on the previously documented vocal parameters.
An area of particular interest has been the potential effect of thyroplasty on vocal
fatigue/effort. In an attempt to quantifi. vocal fatigue and increased effort, three different
parameters were utiiised. It was postulated that d e r thyroplasty, reduced effort would be
reflected by a reduction in phonation threshold pressure, an increase in the duration of
reading time and a reduction in a perceptual rating of effort.
Research Hypothwes
The present study was designed to investigate the following research hypotheses:
1) Subjects with a compensated UVFP will have a stable but reduced fùndarnental
fiequency range compared to established normal values.
2) Subjects with a compensated UVFP will have a stable but reduced intensity capacity
compared to normal values.
3) Subjects will demonstrate an increased area within a voice range profile after
thyroplasty compared to the pre-intervention state.
4) Effort will be reduced after thyroplasty as measured by three parameters
i.) perceptual rating of effort, ü.) phonation threshold pressure measurements, iü.) reading
tirne.
METHODS AND MATERIALS
Study Design
This prospective study was designed to investigate the dysphonia associated with a
compensated d a t e r a i vocal fold paralysis and the subsequent effect of a medialisation
thyroplasty on vocal function. The study design was a repeated single subject paradigm with
each subject acting as his or her own control @re-intervention) compared to the pst-
intervention evaluation. Due to the extreme heterogeneity of the dysphonia observeci in
unilateral vocal fold paralysis (üVFP) subjects (Colton & Casper, 1990; Gray e t al., 1992;
Hirano & Bless, 1993) and small numbers of subjects available, a group cornparison of data
is problematic and the use of a single subject design is preferable (Reynolds & Keams,
1983). The study design is, more specifically, an A-B w i h subject study, which includes a
defined pretreatment assessment of specific voice characteristics, description of the treatment
and post-treatment reassessment-
Participants
Participants for this study included five adult females who ranged in age fiom 42-61
years and one adult male age 40 years. Ail participants were recniited fiom the patient
population referred to the investigator for tertiary evaluation and potential treatment of their
dysphonia. Individuais who presented with a confkmed unilaterai vocal fold paralysis
(UVFP) of more than six months but less than two years duration and who also met the
following inclusion critena were considered as potential participants: 1) between 25 and 65
years of age, 2) unilateral vocal fold paralysis due to a recurrent nerve paralysis determined
by history, physical and radiological examination(s), 3) previously consented for
medialisation surgery, 4) no active pulmonary disease, 5) no prior history of laryngeal
patholom or voice disorders, 6) no history of speech, language or hearing problems, and 7)
native English speakers. The subjects' age, sex, duration and etiology of dysphonia are
summarised in Table 1,
Table 1. Age, Sex, Duration of Symptoms and Etiology for Six Subjects
Subject Age Sex Duration Etiology (mon th )
1 55 F 12 Idiopathic
3 60 F 16 Idiopathic
4 48 F 8 Idiopathic
5 40 M 15 Trauma
6 61 F 6 Thyroid Ca*
Note: *Thyroid carcinoma with known RLN sacrifice
Medical Evaluation and Data Collection of Participants
Indirect laryngoscopy was performed on all participants by the p ~ c i p a l investigator
to document and confirm the presence of a unilateral immobile vocal fold during both
respiration and phonation. During visual examination, the vocal fold may have been observed
to move passively with airflow but no active adduction during attempts at giottic closure or
abduction during normal respiratory efforts were noted. Additionally, each subject's medical
history was obtained and reviewed by the principal investigator, to confirm the onset,
etiology, and symptoms of the presenting dysphonia were consistent with the diagnosis of a
UVFP. If the cause of the UVFP was not clearly apparent in the medical history, M e r
evaluation was undertaken. In such cases, additional radiological examinations of the head,
neck and upper mediastinum were performed to determine the etiology of the RLN
dysfunction.
There was no change in the management of the subjects' dysphonia if they chose to
become a participant in the study. Infomed consent was obtained for each participant at the
time of initial evaluation for inclusion in the study according to the Research Ethic Board
guidelines. Of 18 consecutive patients with the diagnosis of UVFP who underwent
medialisation thyroplasty between March 1997 and July 1998, six participants (5 females and
1 male) met all inclusion criteria and were M e r evaluated as part of this study.
Al1 participants were evaiuated on two separate occasions pnor to the medialisation
surgery at three months (Prel) and at one month (Pret) prior to the scheduled medialisaiion
surgery. Subjects 1 and 2 had only one preoperative evaluation due to distance and expense
involved in travel to our centre. Al1 subjects were evaiuated on two occasions postoperatively
at one-month (Postl) and four to eight mon& (Post2) d e r the surgical date.
The investigator intewiewed al1 potential participants. The symptoms and duration of
the voice disorder and possible etiology were noted. Upon selection for inclusion into the
study, consent was obtained fkom each subject and a standard data collection protocol (see
Appendix A) was administered at each evaluation. AU experimental voice data were
collected by the principal investigator assisted by a certified speech-language pathologist,
during a 1.5 to 2 hour session at the facilities of the Voice Disorders labontory at St
Michael's Hospital, Toronto, Ontario. The experimental protocol included: 1)
videostroboscopy, 2) digital voice recording of sustained vowels, 3) determination cf Fo and
intensity range, 4) modified voice range profile, 5) aerodynamic measures, and 6) reading
task. One rest period was provided for the subjects duriug the evaluation as indicated on the
data collection sheet (Appendix A).
Videostroboscopic Examination
Videostroboscopy was performed on each participant in each session to CO- the
diagnosis of UVFP and document lqmgeai posture during phonation. Dming tbis procedure,
the subject was seated in an examination chair at approximately 45-degree angle. A contact
microphone was placed on the side of the neck over the thyroid lamina for synchronisation of
the voicing with the stroboscopic iight. A lavalier type microphone was clipped to the
participants' coilar to record the audio signal.
Endoscopy of the larynx was performed using a 70° telescope ( Storz) attached to a
single CCD chip camera (Storz model 2 12 13 SL ntsc) with a C clamp connecter. A
stroboscopic light source (Kay Elemetrics model EUS 9100) was used for illumination during
indirect laryngoscopy. The rigid telescope was placed in the oropharynx with the subjects'
tongue held by the examiner with gauze. The image was recorded on a S-VHS video recorder
(JVC S-VHS model HR-S9400U). If visualisation was difficult due to gagging, topical
anaesthetic (4% Iidocaine) was applied to the pharynx. If, however, it was not possible to
obtain a full view of the larynx using the rigid teiescope, then a flexible nasoendoscope
(Olympus Mode1 ENF Type P3) was used. In this situation, the flexible endoscope was
passed through the nasal cavity into the oropharynx and moved inferiorly until a symmeetric
view of the larynx and the M l iength of the normal folds were clearly visualised. Most
participants had stroboscopy performed with the rigid telescope however, Subject 4 had to be
evaluated with the flexible endoscope during two sessions (Pd and Postl).
The videostroboscopic exam protocol consisted of observation of larynged function
under different speech tasks including normal respiration, deep inspiration/expiration, and
sustained voweV i, at habihÜil pitch and loudness. Laryngeal diadochokinesis was then
evaluated by asking the participants to produce seven rapid repetitions of the voweihd (Le. /i-
i-i-i-i-i-il) followed by a similar task which required the participant to repeat the aspirated
vowel /hi/.
As part of a standard clinical protocol, the stroboscopic images were rated jointly by
the author and speech language pathologist to confirm the laryngeal posture during phonation
and document the abnormalities. Monnation on the position and size of the glottal gap were
relevant to planning surgicd treatment and document the change &et thyroplasty fiom the
placement of the silssticR block. The foiiowing characteristics were rated on the stroboscopic
recordings:
1 ) Relative size of the glottic gap compared to the length of the normal fold at the mid and
posterior fold level during comfortable phonation (Omori et. al., 1996).
2) Shape and position of the glottal gap (Figure 2).
3 ) Supraglottic activity 5 point rating scale (Ramos & Bless, 1998).
Acoustic Data Collection and Anabsis
Digital voice recordings were gathered in a sound-treated audiometric booth in the
Voice Disorders Laboratory. Each participant was seated codortably in an adjustable chair
at an examination table to maintain constant posture. AU acoustic data were recorded with a
head mounted microphone (AKG Acoustics, mode1 C4 10) placed at a 90 degree angle to the
left labial angle with the microphone end placed at 45 degrees to the corner of the mouth and
out of the air Stream (2 cm fiom the lip). The subject was asked to produce three tokens of
the sustained vowel /a/ at a comfortable pitch and loudness for five seconds. Ali productions
were digitally captured using the Multidimensional Voice Program (MDVP) (Kay Elemetrics
Versionl.34, 1993). The sampling rate was 50 KHz with 16 bit quantization.
The acoustic data were collected to assist in establishing that the vocal fiuiction of the
subjects in this study was stable prior to and after thyroplasty. Further, changes obsewed in
habitua1 fundamental hquency and perturbation measures assisted in interpreting other data
collected as part of this study
Each digital recording was trimmed to eliminate the first 100 msec of voice onset-
Voice onset characteristically has an increased level of variability and is traditiondy
excluded prior to acoustic analysis. Acoustic analysis was completed on vowel segments of
1000msec. Each trimmed isolated vowel token was analysed for hdamental fiequency (Fo),
percent j itter(JIlT) and percent shimmer (SHIM).
In Subjects 2 and 3, the preoperative vowel tokens were perceptudy judged to
display diplophonia and could be shown to have two major fiindamental frequency peaks on
histogram analysis, The analysis done with the MDVP demonstrated pitch halving where the
program had dif'fïculty identifjhg each phonatory cycle. These samples fiom Subject 3 (Prel
and Pre2) and Subject 2 (Prel) were re-analysed after trimming the nrst 500-1 500msec in
order to eliminate the pitch halving effect. In some of the samples, perturbation values (JXTT
and SHfM) were above 5% and therefore not suitable for analysis and reporting (Schmidt &
Titze, 1994). After analysis, the desired acoustic parameters (Fo, JITT, and SHIM) were
averaged for the three-isolated vowel tokens.
Measurement error d y s i s was completed on three study sessions, chosen at
random. There were no differences in values obtained using the MDVP data between
repeated rneasures.
Fundamental Frequency Range
Fundamental fiequency range, which includes modal and falsetto phonation but
excludes glottal fiy, was obtained fiom each subject as the supporthg data to investigate the
first hypothesis of this study, that UVFP subjects would have a reduced Fo range. The
headset and microphone were placed as descnbed previously and the Real-Pitch program
(Kay Elemetrïcs Version 1.34, 1993) was utilised. The subject was asked to phonate the
vowel /a/ starting at a comfortable pitch and to güssande or glide up to the highest possible
note, then to glide down to the lowest possible pitch without allowing the voice to become
rough or gravelly (glottal f iy register). Once the principal investigator demonstrated the task the participant was then asked to perfonn one practice triai of the task. Whenever possible,
this task was completed during one breath. Subjects 2 and 3 required more than one breath to
successfully complete the task due to excessive air leak. In this case, the task was modified
by separating the continued glide up/down into distinct steps. The participant was asked to
glide up to the highest note possible fiom theu comfortable pitch or to glide down to the
lowest possible note. Three trials were perfomed to establish the fundamentai fkquency (Fo)
range.
The Fo range and cornfortable pitch level were expressed in both Hertz and semitones
(ST) since keyboard cueing was utilised for the voice range profile.
In addition to the Fo range task, the sustainable hdamental Erequency range was
elicited from each participant The ST closest to the maximum hdarnental fkequency
dernonstrated during the glissande task was cued to the subject using a keyboard. The subject
was asked to sustain /a/ at the target pitch for a minimum of three seconds. If the subject
could not sustain the note for at least three seconds, they were cued to one ST Iower and so
on until the maximal sustainable value was established and recorded- The same procedure
was repeated to establish the minimum sustainable fiandamental frequency level in ST. From
these two values, a sustainable fundamentai fiequency range was calcuiated in semitones.
Voice Range Profile
The voice range profile is one method of describing the maximum performance of an
individual's vocal capacity. Usually, the voice range includes calculating the dynamic range
fkom the lowest (excluding glottal fry) to the highest sustainable fundamentai fiequency in
ten percentile increments. However, because the participants in this study were not capable
of completing a Ml voice range profile due to vocal fatigue and discodort, a modified voice
range profile (VRP) was performed at three fimdamental fkequency levels: habitua1 (Fa,
maximal sustainable (FoMAX), and minimum sustainable (FoMIN). Hypothesis 3 of this
study concerns an anticipated increase in the area within the modified voice range profile
after thyroplasty compared to the presurgical state.
Dynamic range was determined at three fiequencies during the VRP data collection.
The second hypothesis of this study was to determine if the intensity range in the
compensated UVFP subject is below the normal value (30-40dB). A hand held sound
pressure level rneter (Redistic mode1 33-2050) was held perpendicular to the airflow and
30cm from the participants' mouth. The investigator stood to the side of the seated subject
with the response selector set on C-scale and on 'fast' response. The participants were tested
at FoH, FoMAX, and FoMiN with pitch cueing fiom a keyboard. Maximal and minimal
intensity levels were fïrst established at the FoH, followed by FoMAX, then FoMIN. Subjects
were asked to produce /a/ at the cued pitch level as loud as possible without screamhg (three
trials) and the result was recorded as maximum intensity in dB SPL. For minimal sustainable
intensity, the subject was asked to produce the vowel as softly as possible without
whisperïng.
The modified voice range profile in this study represents the intensity capacity
(sofiest and loudest) at the three tested fkquencies. Typically, results are plotted in a graph
with Fo on the x-axis and intensity on the y axis. The area within the modified voice range
profile can be caiculated using the formula for a rhombus. The area beneath the line joining
the maximum intensity level for the FoMIN and FoH (down to the x-axis) forms a rhombus
(Figure 3). The area beneath the line joining the minimum intensities for FoMIN and FoH
forrns a smaüer rhombus within the iarger one, The ciifference between these two areas
represents the area within the voice range pronle between the F&EN and FoH (area B). A
similar calculation was done to establish the area within the voice range profile between the
FoH and the FoMAX (area A). The sum of area A and area B is the total (T) are within the
VRP.
Formula 2.
For example, if (xioyl) and (xZ,y2) represent two points of the rhombus, then the other two
points of the rhombus would be on the X axis i.e., (xi, 0) and (xz,O). The formula above
(Formula 2) was used to caiculate the area of each rhombus.
The srnalier rhombus enclosed within the larger rhombus was subtracted to calculate each
area A and area B of the VRP. The results for areas A, B and T are summarised in table form
in the Results Chapter.
Voice Range Profile
Figure 3. Voice Range Profile-Area: B = area beiow FoH, A = area above FoH
Aerodynamics
Maximum phonation tirne is the most cornmonly reported method of demonstrating
an increase in air leak (airflow) during phonation and has been shown to irnprove after
thyroplasty in UVFP. Maximum phonation time (MPT) was performed to demonstrate that
this study population will be observed to have the anticipated increase in MPT after
medialisation thyroplasty, as documented in other subjects with UVFP.
Simuitaneous measurement of maximum phonation tirne (MPT) and airflow volume
was obtained uskg the Nagashima Phmatory Function Analyzer @FA, model PS-77H). An
anaesthetic mask was placed over the mouth and nose and held by the participant firmly over
the face to prevent air leak. Normal values are 25-35 seconds (Hirano 1981). A review by
Hirano (1 98 1) indicated that 75% of UVFP subjects were shown to have a MPT value of less
than ten seconds, however the range reported was fiom 2 to 42 seconds.
The participant was instmcted to take a breath twice as large as normal and to sustain
/a/ as long as possible. The maximum phonation time and total volume exhaled were
recorded. The time in seconds was recorded by a handheld stopwatch as weil as monitored on
the PFA. At least one practice trial was done followed by three trials during which the
measurernents were recorded. The longest MPT was reported as MPT-MAX.
Effort Data
Phonation Threshold Pressure
Phonation threshold pressure (PTP) is defined as the minimum subglottic air pressure
required to initiate phonation. The fundamental fiequency has been shown to effect PTP
resdts. In general, a higher fbndamental fiequency, and m e r vocal folds, the higher
subglottic pressure is required to initiate vocal fold oscillation (Titze, 1994). This measure
directly relates to the fourth hypothesis of this study concerning effort in UVFP nibjects and
a hypothesised reduction in effort &er thyroplasty. Phonation threshold pressure is also an
aerodynamic parameter and can be used to indicate poor glottal closure.
The Aerophone II (Kay Elernetrics Version 1.34, 1993) was used to calculate the
phonation threshold pressure (PTP). Flow calibrations were calibrated using a 1 -litre volume
at the start of each data collection session. The ambient rwm temperature was also entered as
part of the calibration process since this has an effect on the volume and air pressun.
Minimum subglottic air pressure requùed to onset vocal fold oscillation was based on
using inîraorai pressure as an estimate of subglottic pressure. This estimate has k e n shown
to be reliable using ineaorai pressure during a bilabial consonant produced during a train of
consonant-vowel syliables such as /pi pi pi/. This method is a modification of the work done
by Smitheran & Hixon in 198 1.
Prior to fitting the mask, the subject was instnicted to produce a syllable train /pi pi pi
pi pi pi pi/ using a metronome set at 92 beats per minute. The subject was instniccted to start
using normal articulation of the syliables but without producing voice. The subjects were
instructed to introduce voicing at the quietest possible level and graduaily increase the
loudness. The investigator demonstrated and several practice nins were performed.
The AerophoneII was fitted by placing the mask over the face, firmly covering the
mouth and nose and held by the subject. The mask was fitted with an intraoral tube that is
placed cornfortably between the lips and over the tongue. The equipment simultaneously
records intensity, M o w and intraoral pressure and displays al1 three tracings in real time on
the cornputer screen.
Recording began after the subject was cued by keyboard at the desired pitch level.
The PTP was performed at FoH, FoMAX and FoMIN.
The phonation threshold pressure was calculated fiom the f h t pressure peak prior to
a sharp increase in intensity level. This indicates the subject has initiated voicing of the
syllable. If the baseline of the pressure recording was elevated fiom the baseline during the
syllable train, this baseline elevation was subtracted fiom the indicated peak pressure level.
The peak pressure levei during the bilabial consonant of the k t syllable in the train with
voice onset was recorded as the PTP. Durhg the bilabial consonant pressure peak, airflow
and intensity should be zero. The accompanying vowel was evaiuated for the midpoint
intensiw level and recorded as the PTP intensity in dB. Generally, the mid point of the vowel
was at a stable intensity level. In some circumstances, a value was chosen at a stable section
of the vowel if fluctuation in intensity was observed at the onset (see Appendix E).
Reading Task
The purpose of the reading task was to determine if W F P subjects wodd experience
vocal fatigue expressed by throat or neck pain, loss of intensity or hyperventiiation during
prolonged phonation and to quantify the amount of time the subjects' could sustain
prolonged phonation at a reiatively high intensity level.
The subject \vas requested to read the Rainbow Passage aloud in a repeatted fashion to
a maximum of 20 minutes. Speaking rate was not controiled. No attempt was made to
influence pitch Ievel, Intensity levei was controiied by req&g the subject to maintain an
intensity level in the upper 10 dB of their cornfortable pitch intensity range. The principal
investigator used the sound level meter held in the same mannet described for the VRP data
collection. The examiner used gestures to indicate if an increase or decrease in speaking
intensity was required d-g the task. A maximum phonation time (MPT) with total airflow
volume measurernent was performed prior to starting the reading task and at five-minute
increments during the reading task or at the tennination of the task
The reading task was terminated if the subject felt short of breath, experienced
significant neck discodort, became extremely dysphonic or could not maintain the intensity
level within 5 dB of their upper Uitensity range. Otherwise, a maximum time of 20 minutes
was arbitrarïly chosen as the end of the task. Normal subjects can read for up to two hours
without cessation of phonation due to voice fatigue.
The reading tune was reported as the totai time in minuteslseconds that a subject
could read aloud within the upper 5 dB of their FoH intensity maximum. One readuig task
trial was done at the end of each study session. The MPT values were recorded but were not
observed to change during the reading task.
Perceptual Effort Rating
Listenets.
Three normal-hearing young adults (25-30 years of age) served as judges. Al1
listeners had some howledge of disordered voice and speech, but none had more than two
years of experience. Al1 listeners reporteci a negative history of hearing difficulty or
problems.
Procedure (Construction of Stimuli).
Prior to construction of the stimulus tape for percephmi evduation, vowel samples
were extracted and duplicated as described in the Methods section (Acoustic Data
Collection). Vowel stimuli used in this perceptual assessrnent were the same used for the
acoustic data described in the methods (See Methods, Acoustic Data Collection). Habinial
fundamental fkequency included three samples each of the vowel /a/ recordeci at three
specific times (two preoperative recording sessions and one postoperative recordhg session).
Thus, for each of the six speakers who participateci in tbis investigation, nine vowel samples
were obtained. This resulted in a total of 54 samples obtained. For the purposes of this phase
of the study, however, the three c'blocks" or samples (Prel, Pre2 and Post2) were utilised. As
such, these 18 blocks of stimuli (3 blocks X 6 speakers), dong with two additional and
randomly selected blocks for reliability purposes, were randomised and duplicated for
perceptual evaluation. Consequently, 20 blocks were evduated in this phase of the study.
The scale use for the perceptual phase of this investigation was a 9-point, equal
appearing interval scale, which addressed "vocal effort.'' This scale was anchored with
appropriate descriptive terms that sought to denote the extrerne end points of a given feature
(e-g., No Effort = 1, Extreme Effort = 9).
Stimulus preparation.
Duplication of speech analysis was done by routhg the MDVP vowel token samples
into digital audiotape @AT) via a DAT recorder player. Each block of vowel samples (n = 3)
was identified by a number which was then foliowed by an interval of approximately 10
seconds.
Perceptual evaluation.
Prior to perceptual evaluation, listeners were infiormed that they would be presented
with a series of 20 vowel samples produced by adult speakers. Listeners were informed that
they would hear a stimulus number, which would then be foliowed by three productions of a
vowel. Listeners were informed that each vowel sample within a given stimulus block were
not duplications, but rather, sequential productions of the vowel. The listeners were then
asked to provide a rating of the effort level according to the definition provided to them
(Doyle, 1995). Listeners were asked to avoid midpoint ratings, thus, ai i ratings obtained were
whole number values-
Data anaiysis.
Once perceptuai ratings were obtained, the data were coiiated for fûrther d y s e s .
Specific to this anaiysis was the desire to determine any relative change in a given iistener's
rating of vocal effort specific to the tirnes of the voice recording. These data were then
interpreted in respect to time of recording and associated intervention. Mean ratings across
three listeners were calculated for each recording session (Pre 1, Pre2 and Post2) for each of
the six experimentai subjects.
RESULTS
The purpose of this study was to objectively describe the dysphonia associated with a
compensated UVFP and investigate the effects of medialisation thyroplasty on specinc vocal
function parameters.
The study was also investigating the following hypotheses in subjects with a
compensated UVFP: 1) fiindamental frequency range is reduced compared to established
normal values, 2) intensity range is reduced compared to established nonnai values, 3) an
increased area within a voice range profile is observed pst-thyroplasty and 4) effort will be
reduced post-thyroplasty compared to the pre-intervention state.
Results are presented below for the six participants and include acoustic (Fo, JITT,
SHIM, Fo range, VRP area), aerodynamic (MPT and PTP) and effort data (PTP, perceptual
rating and total reading tirne).
The data for hdamental fiequency and intensity range pre and pst-thyroplasty are
specific results in support of the first and second hypotheses respectively.
Voice range profile area data are shown below for each subject pre and pst-
thyroplasty as the basis for testing the third hypothesis. Data on effort evaluation including
PTf levels, perceptual rathg and reading time are reprted in order to test the fourth
hypothesis.
Acoustic Data
Fundamental Frequency
Averaged data for habituai fundamentai fiequency (FoH), mean percent jitter and
mean percent shimmer analysed fiom the isolated vowel /a/ are summarised in Table 2 and
Table 3. The raw data collected at each study sessions for each subject pnor to averaging or
summarising is presented in Appendix D. The acoustic data below represents an average of
the three tokens of the sustained vowel /a/ collected at each study session. In general, the
acoustic data was stable between the first and second preoperative evaluations.
Two of the subjects demonstrated elevated mean habituai hdamental fhquency
(FoH) prior to intervention (Subject 1 and 5) compared to established normal values for their
age and gender (Baken, 1987). Their Fa decreased towards the normal level
postoperatively. Subject 6 was aiso at the upper end of the normal range for her age group
preoperatively (FoH 200Hz). Post-thyroplasty, the Fa for Subject 6 fell to 173Hz, closer to
the average level of 178Hz for ber age group (Pemberton, McCormick & Russeil, 1998;
Ramos Pizarro, 1998).
Two subjects who showed a reduced FoH prior to surgery (Subject 3 and 4) increased
their FoH post-thyroplasty towards normal values. Subject 3 had significant diplophonia
during cornfortable voice production during the preoperative evaluation. Postoperatively the
diplophonia was no longer present In conclusion, five of six subjects were observed to
change their habihial fundamental fiequency towards the normal value for their age and
gender and one subject was unchanged (Subject 2).
Perturbation Measures
Percent jitter and shimmer measures showed increased variability between subjects, a
common observation in studies of dysphonia, relative to n o d subjects. The data shown in
Table 2 and 3 demonstrated that most subjects had elevated perturbation measures compared
to normal values for the MDVP system (e.g. percent jitter 4.04% and percent shimmer <
3.8 1%). The two subjects with the abnormally low FoH pnor to surgery (Subjects 3 and 4)
were observed to have the highest, and therefore, most abnormal perturbation values. These
two subjects exhibited a type 3 signal which is a hi& degree of variability (greater than 5%)
in amplitude, thus making the data inappropriate for analysis using current cornputer
algorithms (Titze, 1995).
Before thyroplasty, the two subjects with the elevated Fa (subjects 1 and 5)
demonstrated the lowest perturbation values for percent jitter and shimmer. Subject 1 was
within normal levels and Subject 5 was slightly elevated for percent jitter but normal for
shimmer. The remaining subjects were al l observed to have elevated percent jitter
preoperatively. Post-thyroplasty, Subjects 1 and 5 remained unchanged (i.e. within nomial
limits) and Subjects 2,3 and 4 were found to have marked reduction in their percent jitter
measures. Subject 6 remained unchanged in this parameter pst-thyroplasty with a
moderately elevated value of 2.802.
In summary, three subjects were observed to reduce or improve percent jitter
postoperatively compared to preoperatively. Two subjects were unchanged and one subject
was found to inçrease slightly afler swgery.
Percent shimmer values were observed to decrease in three subjects, remain
unchanged in one subject and increase in two subjects after surgery compared to presurgical
state.
Table 2. Preoperative Acoustic Data: Habituai Fundamental Frequency in Hertz ( F a Jitter and Shimmer in Percent for Six Subjecb
- - -
Subject Fo in Hz(ST) % Jitter % Shimmer
Prel Pm2 Prel Pm2 Prel Pre2
6 200.5 1 (24) 2 16.29(25) 2.18 2.43 2.77 2.66 Note: *Diplophonia demonstrated with two peaks on Fo histogram and severe perturbation measures, (-) Data not available: see Methods page 33
Table 3. Postoperative Acoustic Data: Habitua1 ~mdamental Frequency in Hertz (Fm, Jitter and Shimmer in Percent for Six Subjcetr
Subject Fo in Hz(ST) % Jitter % Shimmer
Postl Posa Postl Posa Postl Posa - - -
1 239.3 l(27) 203.94(23) I .39 1.19 2.57 >5.0 2 237- 14(26) 226-77(25) 3.37 0.87 4.85 2- 15 3 1 87.06(22) 21 1.61(25) 3.64 1 -93 >5.0 3.59 4 173 .04(2 1 *) 2 12.06(24*) 4.20 2.16 >5 .O 2.49 5 t 33 .00(16) 130.84(16) 0.37 0.51 3.82 3 .56 6 207.24(24) 1 73 -00(2 1) 2.88 2.80 2.68 2.96
Note: *The subject demonstrated a dflerent pitch durhg spontaneous conversational speech when compared to the elicited isolated vowel productions. The chromatic tuner was used to estimate habitual Fo during spontaneous comected speech to v e w the habitual Fo Level. in the Postl and Post2 sessions, the estimated habituai Fo was G3 or 23 in semitones for Subject 4. This habituai Fo was used for prompting during the VRP and PTP measures.
Fundamental Frequency Range
Fundamentai frequency range was determined with three trials of a glissande task to
the maximum and minimum Fo possible by each subject, The maximum sustainable
fiequency (> 3 seconds) was established as the F&UX. Similarly, F m was determined.
For each study evaluation, aU subjects had a total fiuidamental fcequency range estabiished in
semitones (ST) and the results are summarised in Table 4. The pieoperative Fo range was
stable or deteriorated in 3 of 4 subjects fiom the Prel to Pre2 evaluation. Subject 4 exhibited
a 5 ST increase in range.
Four of six subjects had below the acceptable value for fùndamental fkquency range
(less than 20 ST). Normal subjects are often observed to have an Fo range in the order of 30
to 40 ST however (Le. 36 ST Coleman, 1977). Subject 6 had 25 and 26 ST in Fo range prior
to surgery but improved to 29 ST by the Post2 evaluation. Subject 3 had an extremely
reduced Fo range of 6 ST prior to surgery and increased to 14 ST pst-thyroplasty. No subject
was observed to reduce their Fo range after surgery and 4 of 6 subjects were observed with an
Fo range within the normal value.
Table 4. Fundamentai Frequency Range in Semitones: Pre and Post-thyroplasty for Six Subjects
Subject Prel Pre2 Postl Posa
1 18 - 18 25 2 16 - 12 18
3 6 6 10 14
4 16 21 21 21
5 24 18 28 27
6 25 26 26 29
Note: Abnomal fiuidamental fiequency range c 20 semitones (Coleman et. al., 1977) (--) Data not available: see Methods page 33.
Intensity Range
Intensity range was determined for each subject at three fiequencies, FoMIN, Fa and
FoMAX. The intensity range summarised in Table 5 represents the minimum and maximum
intensity at any of the tested fiequencies. Normal values of dynamic or intensity range in
aduits vary between 40-55 dB (Baken, 1987). The dynamic range for the study participants is
shown in TableS. Subject 6 had a dynamic range of 39 dB prior to surgery and increased
postsurgery to 44 and 46 dB in the Postl and Post2 evaluations. Al1 six compensated UVFP
participants were observed to have a reduced dynamic range. Although dl subjects increased
in intensity capacity postsurgery (range 2-lOdB), five of six remaineci below the normal
value.
Table 5. Intensity Range in dB SPL: Pre and Post-thyroplasty for Six Subjects
=3L
Subject Prel Pm2 Postl Posa
6 39 41 46 44
Note: (-) Data not available: see Methods page 33.
Voice Range Profile Area
A modified voice range profile was performed with three muency levels: minimum,
habituai and maximum since pilot data indicated that compensated UVFP subjects were
unable to complete the VRP with tenth percentile increments of their Fo range. The area
within the voice range prome (VRP) was calculated according to Formula 2 (see Methods
section) and is summarised below in Table 6. Table 6 shows the two areas (A and B)
calculated within the VRP. Area B represents the area between the maximum and minimum
intensity range, fiom FoMIN to FoH. The other portion of the VRP is termed A and represents
the area between the FoH and FoMAX.
The total area within the VRP (A + B) for each subject and data collection session is
Iisted in Table 7. AU subjects showed an increase in the total area within the voice range
profile after thyroplasty compared to the presurgicd evaluation. Participants demonstrated a
different combination of fkequency and intensity range alterations pst-thyroplasty to account
for the expansion of their VRP area.
Subject 1 showed an increase fiom 373 to 568 in the total area within the VRP. Most
of this change was within the area between the FoH and FoMAX or area A. intensity values
did not change significantiy but the frequency range in this portion of the VRP was increased
from 8 to 20 semitones by the Posd session,
Subject 2 had a modest increase fiom 21 1 to 267 postoperatively in total VRP area
The increase in area was Iargely due to an increase in intensity capacity at the subjects'
habituai Fo (see Appendix D).
The area between the minimum sustainable and habituai fiindamental fkquency
levels (B) showed marked improvements in Subjects 3,4,5, and 6. For Subject 3, this change
is attributable to the marked increase in total fiequency range fiom a severely restricted 6 ST
in the Prel session to 14 ST pst-thyroplasty. Although this value is stili well below the
normal mean value of 36 ST, (Coleman et. al 1977), nonetheiess this subject realised an over
350% increase in VRP area Maximum intensity values also increased moderately at dl three
fiequencies tested for Subject 3.
Prior to thyroplasty, Subject 4 could produce a FoMM level at only one semitone
below her habitua1 Fo (FaH). Therefore, the B portion for this subject was extremely small
but increased ten fold fiom 8 to 84 pst-thyroplasty due to the increase in FoH by 5 ST. Also,
the VRP area was increased due to an improved dynamic range paaicularly at F&MX.
Subject 5 was the o d y subject to show a marked ciifference in performance in the
VRP task between the Prel and Pre2 sessions with a reduction fiom 404 to 192. Frequency
range was reduced at both ends as well as modest reduction in dynamic range at the habituai
and maximum fiequency levels at the Pre2 evaluation. This subject stated that his vocal
dysbction was getting worse and felt that the second session prior to surgery reflected the
detrimental changes. Post-thyroplasty, Subject 5 was observed with a modest increase in total
VRP area to 450- The increase was largely due to the increase in frequency range by 8 ST in
the A area (FoH reduced by 4 ST and FoMAX increased by 4 ST).
The largest total value for VRP area was observed in Subject 6 who increased fiom
508 during the Prel session to 702 at the last evaluation. This subject was a singer who had a
relatively good fiequency range of 25 ST prior to surgery. Post-thyroplasty, the Fo range
expanded to 29 ST with the 4 ST increase at the lower end of the fiequency range (FOMIN
reduced by 4 ST). Ail three fiequencies tested had expanded intensity capacity with a peak
intensity of 96dB at the maximum sustainable fiequency for this subject.
In general, subjects demonstrated an increase in their dynamic range at all three
fiequencies tested post-thyroplasty. Total fundamental kquency range was increased in all
subjects post-thyroplasty. Most subjects (one through five) exhibited an expansion at their
upper Fo range. Subject 6 was observed to increase at the lower end of the Fo range ody.
Table 6. Modifïed Voice Range Profüe Area: Below (B) and Above (A) Hlbitual Fundamental Frequency for S u Subjects
Subject Prel Pre2 Postl Posa
B1A SIA BIA BIA
1 1651208 - 147/33 1.5 97.51470
6 3 61472 -5 1 141440 100/588 92.51609.5 Note: (-) Data not available: see Methods page 33.
Table 7. Modified Voice Range Profile-Total Area for S u Subjects
Subject Prel Pre2 Postl Posa
6 508.5 554 688 702 Note: (-) Data not available: see Methods page 33.
Pre 1 Pre2 Post 1
Figure 3. Voice Range Profile: Total Area Pre and Post-thyroplasty for Six Subjects
Aerodynamic Data
The aerodynamic data included maximum phonation time (MPT) and phonation
threshold pressure that is inçluded with the effort data described below. R e d t s of MPT
testing demonstrated an increase (ranging fiom 3 to 9 seconds) for ai i subjects pst-
thyroplasty shown in Table 8. Overall, the MPT values were observed to be consistent fiom
the Prel to the Pre2 evaluations. W l e improvement was noted fkom pre to postsurgery, five
of the six subjects were consistentiy outside reported normal values (Hirano, 198 1).
The pst-thyroplasty increase in MPT confirms the expected reduction in glottal air
leak after rnedialisation of the pardysed vocal fold.
Table 8. Maximum Phonation Time in Seconds: Pre and Post- thyroplasty for S u Subjects
Subject Prel Pre2 Postl Posa
6 10.95 10.33 20.28 19.09 Note: (-) Data not availabie: sec Methods page 33.
Effort Evaluation
Phonation Threshold Pressure
Results for phonation threshold pressure (PTP) for al1 six subjects at the lowest
sustainable (FoMIN), habitual (FoH) and maximum sustainable (FoMAX) fitadamental
fkequencies are included in Tables 9,10 and 1 1. The results for phonation threshold (PTP)
were unpredictable and varied with each subject therefore the results wiU be discussed
individuail y.
Normal values are dependent in part on the Fo tested. In general, habitual pitch testing
have shown PTP levels between 3 and 6 cm HzO (Gramming, 1988; Titze, 1994). As Fo rises,
there is a corresponding increase in PTP level. High Fo PTP values are generally greater than
6 c-O, while FoMIN and FoH have been reported at a mean value of 3.3-3.5 cm&û
(VerdoLini-Marston, et. al., 1990). Also, as intensity increases, subgiottic pressure also rises.
Subject 1 demonstrated normal PTP values when tested at cornfortable Fo and
FoMAX with a slight increase fiom the Prel to the Post2 session. This subject had difficuity
success fully completing the ta& at the minimum sustainable fundamental fiequency level,
The subject could not perform the task at the correct Fo in the preoperative session.
Subject 2 showed normal PTP values at FoMIN during al1 study evaluations. The PTP
value for this subject was found to increase within the normal range after thyropiasty at the
three frequencies tested with greater increases observed for the Fa and F m during the
second po stsurgical evaluation.
Subject 3 showed a reduction in PTP levels at FoMM and FoH levels post-
thyroplasty. A modest increase was observed in the PTP value at FoMAX but al1 values were
within normal levek.
Subject 4 could not complete the task at FoMIN prior to thyroplasty, which was only
one semitone below FoH. The attempts to produce the sequence of consonant-vowel syllables
redted in whisper type phonation. Although there was no change in the PTP values for
Subject 4 during F a testing, the post-thyroplasty FoH Level was increased by 5 ST.
Normally, PTP values are higher with an increase in the fiequency tested. Maximum Fo
demonstrated a slight reduction in PTP for Subject 4 pst-thyroplasty. Further elaboration on
the mechanisms involved in detennining phonation threshold pressure will be expandeci in
the discussion.
Subject 5 did not demonstrate any change in PTP level when tested at FoMIN and
FoH dthough the FoH tested was reduced by 3 ST. At F&lAX, a relative decrease in PTP
level was observed pst-thyroplasty given that the Fo tested was 5 ST higher than pre-
thyropiasty-
Subject 6 was found to have an elevated PTP value at FoMAX pnor to surgery. This
value was reduced pst-thyroplasty. At F m and F a , the PTP level was modestly
increased in Subject 6 post-thyroplasty but fell within the nomial range.
Table 9. Average Phonation Threshold Pressure Valuea (PTP) in cm H20 with Intensity for Minimum Sustainable Pitch (FcMLN) for S& Siibjecb
Subject Pte1 Pre2 Postl Posa
Note: (-) Data not avaiiable: see Methods page 33. (*) Subject could not complete task.
Table 10. Average Phonation Thnsbold Pressure Values (PTP) in cm H20 with Intensity for Habitua1 Pitch ( F m for S u Snbjects
Subject Prel Pre2 Postl Pose
2 3.92(64) -- 5.25(60) 7.35(70)
3 3.33(58) 5.68(54) 4.68(58) 2.68(57)
4 2.92(64) 3.61(58) 3,96(67) 3.49(58)
5 3.09(64) 3.20(66) 2.2 l(60) 3 .07(6 1)
6 4.1 l(66) 6.6 l(67) 2.96(62) 2,77(65)
Note: (-) Data not availabie: see Methods page 33.
Table 11. Average Phonation Threshold Pressure Values (PTP) in cm H ~ O for Maximum Sustainable Pitch @'MAX) for Six Siibjeeb
Subject Prel Pre2 Postl Posa
6 8.19(79) 12.83(79) 5.01(75) 7.77(75)
Note: (--) Data not available: see Methods page 33.
Reading Time
The length of time that subjects were capable of reading aloud in the upper end o f
their intensity range is reported in Table 12. This task was terminated if the subject could not
maintain oral reading within the 5 dB target intensity range or if the subject became
symptomatic fiom vocai fatigue. Subject 1 could complete 20 minutes o f reading doud pre
and post-thyroplasty. Al1 other subjects, (five of six) demonstrateci an increase in readhg
time post-thyroplasty. Five subjects were able to read pst-thyroplasty to the maximum time
recorded of 20 minutes. Subject 2 increased her reading time fiom approximately four
minutes to 15 minutes postoperatively.
Table 12. Reading T h e (minutes. seconds): Pre and Post-thpplasty for Su Subjects
--
Subject Prel Pre2 Postl Posa
6 20.00 10.00 20.00 20.00
Note: (-) Data not available: see Methods page 33.
Perceptual Effort Rating
The overdl pre to postoperative cornpanson indicated improved pediomiance
according to the parametedfeature of vocal effort by perceptual rating in four of six subjects.
In three of the subjects (2,3 and 4), the data presented in Table 13 clearly show that
substantial decreases in effort were obsewed. Although Subject 1 also showed a decrease in
effort, this change was not as ciramatic as that seen in the other three subjects. Subject 6 did
not show a substanttial change fiom pre to pst-thyroplasty. Subject 5 showed a slight
increase in effort rating d e r thyroplasty.
In regard to reliability of perceptual judgements obtained, al1 three listeners gave
identical ratings for the duplicated samples used for reüability purposes. Thus, within-subject
agreement was 100% for each listener (two of two). This kding supports the notion that
each listener was using a consistent interna1 measurement for thek judgement of vocal effort,
which adds strength to the present kdings.
Table 13: Percephial Effort Rating: Pre and Posa-Thyropiasty for Su Subjects
Subject Pre 1 Pte2 Posa
1 2.3 4.0 1.7
CHAPTER N
DISCUSSION
This prospective study was performed to investigate the vocal characteristics of the
dysphonia associated with a compensated unilateral vocal fold paralysis (üVFP) and the
effect of medialisation thyroplasty upon specific phonatory behaviour. The single subject
design was acivantageous in that it permits a small study group to be evaluated in a detailed
fashion for a p e n d of time More and d e r surgical intervention. The participants in our
study had the surgical treatment performed at a relatively consistent t h e after the onset of
W F P symptoms. By selecting subjects with UVFP for at least six months but less than two
years, both structural and behavioural compensation would have already occurred. However,
surgery was performed before two years fiom omet, the time at which atrophy of the affected
muscles couid become apparent with possible M e r deterioration of vocal b c t i o n (Hirano
& Bless 1993).
Baseline Measurements Pre-thyroplasty
Repeated assessrnent of compensated üVFP subjects prior to intervention was
completed to establish that the vocal fûnction was stable. Four of six subjects had two
preoperative study evaluations. The other two subjects (Subject 1 and 2) had one
preoperative evaIuation due to tirne and expense to travel to our centre.
In general, the vocal function of the study group was observed to remain stable when
the individual data are reviewed. Hence, the study sample of compensated W P subjects
demonstrated a stable baseline in vocal fuaction. Reported changes in vocal fiinction after
medialisation thyroplasty, if they occurred, cm be reliably attributed to a direct effect fiom
the surgery.
The acoustic data collected (Fo. JiTT and SHIM) between the fkst and second
preoperative sessions (Table 2) remained stable for al1 subjects. The Fo range fiom Prel to
Pre2 showed no increase in three of four subjects indicaîing no M e r spontaneous
improvement. Subject 4 demonstrated an increase of 5 ST in Fo range fiom Prel to Pre2.
Factors which may have Hected the Fo range in this subject include variation in vocal fatigue
and motivation (Coleman, 1993). This subject was a teaching professor with moderate to
heavy voice demands that may have affected her performance at dinerent study sessions.
Expected variability (normal abjects) is 12 ST if retested within the same &y and can be
larger if tested within four to six weeks (Coleman, 1993). Three of four subjects who
completed both preoperative evaluations were within reported expected variability (one
standard deviation of 3 dB) in intensity range (Gramming, & Sundberg, 1988).
The foLlowing parameters, maximum phonation tirne, modifieci voice range pronle
total area and total reading t h e showed no improvements fiom Prel to Pre 2 in aii subjects.
The phonation threshold pressure values generally were inciined to main unchanged
(within one cmH20) or increase fiom the Prel to Pre2 study evaiuations. While these changes
might be attributed to expected test, re-test variability, other possibilities exist and are
discussed below (see page 79).
Fundamental Frequency Range
The first hypothesis of this study predicted that subjects with a UVFP would have a
stable but reduced fiindamental fiequency range pnor to surgery compared to established
normal values. Coleman et. al., (1977) estabiished that the normal fiequency range in adults
may extend to 40 semitones, but when below 20 semitones, fimdamental Erequency range is
abnormal. In this study, five of six subjects had a fiindamental fiequency range less than 20
semitones prior to surgery. Therefore, the results support with the first hypothesis, that
compensated UVFP subjects will have a reduced fimdamental frequency range.
Limitations in overall Fo range in the present study followed a specific trend. Five of
the six subjects were observed to have an elevated minimum fundamental fiequency level. In
other words, most of our subjects had great difficulty when attempting to phonate at a lower
Fo level. This has been previously reported in the literature by Hirano (1981) who found that
in W P , the minimum sustainable Fo level was elevated and attributed to the lack of TA
activity.
Intensity Range
in Coleman e t ai., (1977) normal adults were reported to show an intensity range of
over 50 dB SPL in both men and women although in clinical practice, an intensity range
below 40 dB is considered abnomial. Five of six subjects were obse~ed with a dynamic
range below the normal range as described by Coleman et. al., (1977) with Subject 6 just at
the lower end of normal. Therefore, the data supports the prediction by the second
hypothesis, that subjects with UVFP will have a reduced intensity range compared to
established normal values pnor to surgical intewentïon, In this study, the intensity range
varied from 13 dB SPL in Subject 3, to 41 dB SPL in Subject 6 preopetatively. Ail subjects
subjectively reported that their loudness had been reduced since the onset of the unilateral
vocal fold paralysis. The minimum intensity level at the three tested fkequencies (FoMIN,
FoH and FoMAX), was withui the normal range (Baken, 1987). Maximum htensity levels
were below normal values (approximately 100 - 1 15 dB, Baken, 1987) for al1 subjects prior
to surgery.
Stabiiity of Measurements Post-thyroplasty
The first pst-surgical study session was completed one month after the surgical date.
The second post-surgical evaluation was done between three and eight months after the
surgical date. Some of the vocal fûnction parameters evaluated were found to change fiom
Postl to Post2. For the most part, the direction of the changes pointed towards m e r
improvements in vocal function. The continued improvements observed by the second
postoperative visit are likely due to further behavioud adjustments d e r the medialisation
procedure (Karneli, et. al., 1 997). Other factors, which may have affected the results fiom the
first to the second postoperative study assessment, include m e r reduction in swelling
andor discornfort related to the surgical procedure. Discomfoa may have Limited the
subjects' performance on maximal performance tasks such as reading time or diffIcult tasks
such as PTP evaluation. Because the second postsurgical session was not held for several
months (three to eight months), the data at that time likely represents a stable status in vocal
function due to both the direct and indirect effects of thyroplasty.
For example, hdarnental fiequency range, intensity range, reading t h e and VRP
area data were unchanged or showed M e r improvements h m the Postl to the Post2
evaluation. Phonation threshold pressure changes h m Post 1 to Post2 were mixed and
M e r details are discussed below. The postsurgical changes in vocal fiinction as assessed by
the parameters in this study appeared to be stable and in some cases, continue to improve by
the second postoperative evaluation. Further discussion of the changes in vocal fünction fiom
pre to postoperative follows.
Cornparison of Vocal Function Measurements Pre to Post-thyropiasty
Voice Range Profile
As predicted, the results demonstrated a clear improvement with an increase in voice
range profile area after medialisation thyroplasty. The third hypothesis of this study, which
predicted an increase in VRP area af3er thyroplasty compared to pre-thyroplarty, was
supported. Since the voice range pronle is a method of combining two intrinsically related
parameters, fundamental fiequency and intensity, effectively summarised an overall
improvement in vocal function after thyroplasty.
Fundamental frequency and intensity range pre to post-thyroplristy.
The main effect of thyroplasty on intensity is primarily through improved glottic
closure and therefore' subglottal pressure capability. If the glottis can maintain a closed
position without significant air leak while pressure is raised undemeath the folds, intensity
capacity will be improved. Since thyroplasty should increase the subglottic and intraglottic
pressure capability, the lateral excursion (amplitude) of the fol& during phonation will also
improve. The increase in amplitude of the folds during the phonatory cycle will generate
more tissue stretch, and rebound the tissues faster towards the midline.
Thyroplasty may also improve phonatory cycle symmetry and if the cioshg phase
becomes more efficient, intensity capacity will be increased. This will speed up the rate of
airflow cut-off during phonation that has been shown to be an important component of
raising intensity (Gauffin & Sundberg, 1989)
improvements in nibglottic pressure, rate of vocal fold ctosiae, and vibratory
symmetry thought to result fiom thyroplasty, would account for the observed increase in
intensity range observed d e r thyroplasty.
The other component of VRP is fundamentai fiequency range. Five of six subjects
showed an increase in Fo range d e r thyroplasty. This concurs with the predicted increase
according to the improvements in vocal fold vibrating length, stBness, mass and vibratory
syrnmetry outlined in the Theoretical Effects of Thyroplasty on Fo (see page 18).
However, thyroplasty did not normalise intensity or fkquency ranges in most study
subjects. Despite improved giottic closure the persistent failure of the aryîenoid cartilage to
adduct in a normal fashion may result in a posterior glottic gap. Although the antenor portion
of the folds may not exhibit any glottic gap during phonation afler thyroplasty, the posterior
glottis often retaios a glottic gap fiom the lack of arytenoid cartilage apposition. Any residud
posterior glottic gap coupled with a TA paraiysis and less vocal fold bulk on the paralysed
side results in an fündamentally asymmetric system. Although vocal fold mass was improved
by the placement of the silasticR block, the fiee margin or edge of the paralysed fold has less
vertical height compared to the normal vocal fold as the TA atrophies. The asymmetry in the
upper and lower edges of the vocal fol& will likely restrict intraglottk pressure capacity and
conûi bute to continued vibratory asyrnme try . The Limitation of thyroplasty remains that the
silasticR block cannot fully adduct the arytenoid cartilage in some cases, nor re-contour the
paralysed fiee edge to rnirror the normal vocal fold.
Habitua1 fundamental frequency pre to post-thyropiasty.
While predictions related to the FoH were not made in this study, results fiom the
standard data protocol were available for examination in an effort to explore the eEects of
thyroplasty. In four of the six subjects, the FoH or habitual pitch was observed to fd after
surgery. This effect after thyroplasty was in part predictable given the changes in pitch
control reviewed in the introduction. If thyropiasty is an effective rehabilitative technique for
a compensated W F P subject, then the changes in Fo after surgery should move towards
normal.
In support of the expected elevated FoH prior to surgery, 4 of 6 subjects showed
supraglottic hyperhction on indirect laryngoscopy attributed to behavioural compensation.
This supraglottic hypefiinction would contribute to increased stiffiiess of the folds, which
mises Fo.
Conversely, two subjects had reduced FoH (Subject 3 and 4) prior to surgery. Of these
two subjects, the Fo nage was severely reduced in Subject 3 (6 ST in Prel evaiuation).
Possible explanations for the observed lower habitual Fo in Subject 3 may have been that she
had a large glottic gap preoperatively, or that this subject had quite limited vocal demands
(Coleman, 1993). Subject 4 was using a habituai pitch at the bottom of her hdamental
frequency range. Normally, the habitual speaking Fo is between the IO* and the 2 0 ~
percentile of the total fündamental frequency range (Stone & Sharft 1973). Motivation was
an unexpected factor that greatly influenced the FaH of Subject 4. She had realised that a
higher pitched speaking voice was easier to produce and provided a louder and less fatiguing
voice but she would not utilise this voice as her habitual voice pnor to surgery since it did not
agree with what she perceived as her 'own voice'. This subject felt that a higher pitched
speaking voice, although more vocaily efficient, was not appropriate for her self-image or
profession. She was able to demonstrate this higher pitched voice and isolated sustained
vowel tokens were recorded for acoustic analysis. Interestingly, this higher pitched voice
showed improved perturbation measures and MPT compared to the habitual voice that she
did utilise. AIthough compensation mechanisms had been developed by this subject, her
auditory percept of a higher pitched voice was unacceptable and was, therefore, deliberately
avoided by this subject prior to surgery.
Effort Assessrnent Pre to Post-thyroplasty
One of the most important indirect effects of thyroplasty in a clinical application
would be a reduction in effort after surgery. The fourth hypothesis of this study stated that
after thyroplasty, vocal effort during phonation would be reduced. Since this is an extremely
complex area to quanti& three parameters were utilised (PTP, reading t h e and perceptual
rating) which will be discussed below.
Reading time.
The reading time results did show a clear increase nom pre to postsurgery in 5 of 6
subjects. The data are convincing in support of the fourth hypothesis, that thyroplasty will
reduce effort during phonation. In the presurgicd evaluations, 5 of 6 subjects were observed
to stop reading aloud due to symptoms of vocal fatigue. if thyroplasty is effective in reducing
excessive behavioural activity which the subjects had developed as part of their
compensation to a unilateral vocal fold paralysis, then it foiiows that vocal effort and fatigue
should also be improved.
Perceptual rating of effort.
Based on the perceptuai data obtained, effort level was judged to decrease in the
postoperative condition for four of six subjects (subjects 1,2,3 and 4). In the case of subject 5,
the post surgery mean rating was increased h m the pre surgery condition. While this mean
increase was not large (4 -5 mean scaled values), the post surgery rating was judged to be
more efforfortful relative to the preoperative state. This subject was able to lower bis FoH by
4 ST post-surgery. He had an elevated FoH preoperatively and it was his primary cornplaint
that he could not lower his speaking voice. M e r thyroplasty, he was able to maintaia a
lower FoH and the increase in effort rating maybe due to his desire to maintain as low an FoH
as possible. Overail, the pre to postoperative comparison indicates improvernent in
performance following thyroplasty according to the parameter of vocal effort in four of six
subjects. It seems apparent that thyroplasty can reduce vocal effort as indicated by the above
results. However, the most difficult parameter to interpret was the results of the phonation
threshold pressure as an indicator of vocal effort.
Phonation threshold pressure.
Phonation threshold pressure reflects the ease with which oscillation of the vocal
folds is initiated. This pammeter was chosen as a iikely objective means of verifying the
predicted reduction in effort after thyroplasty. As is often the case when investigating
pathological conditions, a more complex scenario became evident during this study. Two
dominant factors were suspected of infiuencing the PTP results seen in this study sample.
First, a cornmon behavioural manoeuvre in UVFP observed during phonation was an
increase in supraglottic activity and general inclination for the suspensory laryngeal muscles
to be activated to assist in glottic closure. It was postulateci that the hyperfiinction would
increase the arnount of subglottic pressure required to initiate phonation if the glottic gap was
sufficiently closed by the laryngeal muscles. However, if the glottic gap cannot be
maintained in a closed position (< lmm), it follows that despite the increase in muscle effort
surroundhg the glottis, an air leak may be present In this circumstance, phonation threshold
pressure may be normal or reduced, depending on the Fo tested. Within an individuai's
fiindamental fiequency range, it may Vary as to whether the dominant effect on PTP is the
increase in laryngeal tension fiom compensatory muscle activity or glottic incornpetence.
One element of the P T ' task may be helpful in assisting the interpretation the resuits
for PTP is the intensity of the vowel following the phonation threshold pressure peak. Since
subglottal pressure is the main factor contributing to intensity, a lower intensity value should
be observed when the subglottic pressure is limited. Two patterns of PTP resutts are
discussed below to illustrate the different effect of thyroplasty on this parameter.
The fh t pattern observed in Subjects 1,4,5, and 6 appeared to fit with the
anticipated reduction in PTP post-thyroplasty and was interpreted as a reduction in effort.
Subject 4 was found to have normal PTP values at FoH tested in both pre- and post-
thyroplasty study sessions. However, FoH rose by 5 ST in the postoperative study sessions
for this subject. This represents a relative reduction in PTP &er thyroplasty since a higher Fo
level normally requires a higher subglottal pressure to onset phonation (Titze, 1994). Similar
fmdings were observed in Subject 5 and 6 with a lower PTP value after thyroplasty despite
an unchanged or increase in the Fo Level tested. These three subjects demonstrated the
predicted reduction in PTP after thyroplasty theoretically indicating a reduction in effort to
omet phonation.
The second pattern of PTP change afker thyroplasty was primarily an expected rise in
PTP since the Fo level tested was increased. At FoMAX, Subjects 2 and 3 showed a rise in
PTP level at the postsurgery evaluation explained by an increase in the FoMAX tested (7 and
8 ST respectively).
As stated previously, the ability to generate and sustain subglottic air pressure in
patients with UVFP is, in great part, related to the presence and severity of air leak through
an incompetent glottis. One subject in this series, (Subject 2), showed increased PTP levels
across al1 frequencies tested after thyroplasty. While this finding might be initially
interpreted as an increase in effort, the presence of a large gap prior to surgery would restrïct
the generation of subglottic pressure. The MPT value for this subject prior to surgery was
severely reduced (3.95 seconds), confimiing the presence of substantial air ieak, Since air
leak was the main factor restricting subglottic air pressure d u ~ g the onset of phonation, then
by closing or reducing the glottic gap after thyropiasty, generation of a higher subgiottic air
pressure is possible. In this scenario, PTP appears to fûnction as an aerodynamic parameter,
indicating an improvement in laryngeal resistance and does not necessarily h c t i o n as an
indicator of effort.
PTP values at FoH were largely stable and rernained within normal limits both pre and
post-thyroplasty. These results are not unexpected since at Fa, the phonatory process is
likely functioning at optimal compensation both before and &er surgery. Therefore, PTP
ievels rernained unchangeci (within normal bits) as a reflection of the most efficient
compensated phonatory state.
FoMIN proved to be the most difncult task to complete for most study subjects. Two
subjects (Subjects 1 and 4) while incapable of completing this task prior to surgery had no
difficulty afier thyroplasty. The PTP values for these two subjects at Fo MM were within
expected normal limits. In generai, PTP values at F o W for the other subjects tended to
increase d e r surgery. In hindsight, lowering Fo was a difncult vocal task for UVFP subjects.
In low Fo conditions, there is the least amount of tissue stiffbess, largest potential glottic gap
and likely a greater degree of asymmetry of vibration. Given the inability of UVFP subjects
to maintain glottic resistance at this Fo, it not surprising that, as an indicator of effort, the PTP
results were inconsistent with a predicted decrease d e r surgery. When the vocal folds are in
a state of increased stif3hess Le., at F m , PTP appears to function as a measure of effort
and the predicted decrease in PTP level was observed in most subjects. In conclusion, the
results at FoH and FoMIN did not concur or support the prediction that thyroplasty would
reduce effort by lowering PTP. However, evaluation of this parameter at FoMAX was
consistent with the prediction that PTP values would decrease after thyroplasty.
Study Limitations
One of the Limiting areas of clinical research is the availability of subjects for a
relatively uncornmon disorder, who meet inclusion criteria to fonn a homogenous study
sarnple and are willing to participate in a study. A more ideal study would have been to
compare a larger study sarnple to a similar but untreated control group.
The results of some vocal parameters evaluated in this study wodd have been more
clearly interpreted if, for example, the intensity range had been assessed at the same three
hequency levels that were tested prior to surgery. Also, PTP redts may have been easier tu
interpret if the same three target Fo were tested pre and pst-thyroplasty rather than
establishing a new FoH, F&MX and F m . In fbture studies, subjective assesment of vocal
function could be correlated with some of the vocal measures assessed pre and post-
thyro~lasty-
SeKReported Idormation
Al1 subjects in this study complained primarily of reduced vocal starnina, increased
effort, and reduced loudness. However, Merent aspects of their dysphonia had varying
degrees of importance. The effect of thyroplasty on these mainly self-reported symptoms
was interesting. Prior to surgery, Subject 1 was concemed that her comfortable speaking
voice was irritating in qualiiy despite quite normal acoustic measures objectively. Subject 4
and 5 were most interested in aitering their comfortable speaking pitch towards normal
levels. Subject 6 wanted to be able to r e m to singiag in the community chou- Subjects 2
and 3 complained of dyspnea with speakhg. In general, the subjects were pleased with the
results of the surgery to improve their individual cornplaint. AU subjects felt that although
much improved, achieving normal loudness was still not possible after surgery.
Conclusions
Overall, this study demonstrated that prior to surgery, a fairly Worm study sample
of compensated UVFP subjects had a reduced fundamental frequency and intensity range
compared to published normal values. From an established stable baseline prior to treamient,
medialisation thyroplasty was found to improve but not normalise vocal fünction in most
subjects. An important implication from this study was that despite the natural improvement
which occurs and the individual variability with a UVFP, medialisation thyroplasty was
effective in improving certain parameters of vocal fünction and reducing vocal effort.
S pecific areas that improved are the pitch and loudness capabilities and increased vocal
stamina f i e r thyroplasty. Treatment options to provide M e r progress &er thyroplasty
include behavioural therapy a d o r other surgical methods. Behaviourai therapy may be
beneficial in subjects who have persistent counter-productive compensatory mechanisms and
if formdy investigated, may show the value of therapy to 'fine-tune' a new system after
swgery.
Other adjuvant surgical treatments can address the specifk areas where efficacy of
thyroplasty may be limited. For example, a fkee tissue graft can improve the vertical height of
the fiee edge of the paralysed fold. Arytenoid adduction, a relativeiy new technique, is
reported to close the posterior glottic area, which may be a persistent problem in some
subjects &er thyropiasty. These adjuvant treatments could also be subjected to a formai
evaluation to document ifvocal fùnction measmes can be improved compared to thyroplasty
aione. This might indicate çpecifk advantages of one form of surgical treatment over another
and may assist the cliniciaa in selecting the best treatment based on specific
subjective/objective voice abnormaiities prior to surgery.
REFERENCES
Abelson, T. 1. & Tucker, H. M. (198 1). Laryngeai findings in superior laryngeal nenre paralysis: a controversy. O t o l a ~ ~ o l o ~ - Head and Neck Sureerv, 89 463-470. d
Arnold, G. E. (1 955) . Vocal rehabilitation of paraiytic dysphonia: 1: Cartilage injection into a paraiytic dysphonia. Archives of Otolarynoloey, 62. 1-17.
Baken, R J. (1987) . Clinicai measurement of swech and voice. Boston: Coîiege Hill Publication, Little, Brown and Company.
Ballenger, J. J. (1985) . Neuroloeic disease of the larynx. In: Ballenger, J. J. (Ed.), Diseases of the nose, throat, ear, head, and neck. (5 13-548) . Philadelphia: Lea and Febiger.
Bard, M. C. , McC&ey, T. V. , Slavitt, D. H. & Lipton, R. J. (2992) . Non invasive technique for estimating subglottic pressure and laryngeal efficiency. Annals of Otolorrv. - - Rhinolow and Larvngoloq, 101,578-582.
Benninger, M. S . , C d e y , R. L. , Ford, C. N . , Gould, W., Hanson, D. G. , Ossoff, R H. & Sataloff, R. T. (1994). Evaluation and treatment of the unilateral paralyzed vocal fold. Otolaryngoloev - Head Neck Sureerv, 1 1 1, 497-508.
Berke, G. E. , Hanson, D. G. , Moore, D. M. & Ward, P. H. (1987). Videostroboscopy of the canine larynx: the effects of asymmetric laryngeal tension. Larvnaosco~e, 97 O, 543-553.
Berke, G. S. , Moore, D. M. , Gerratt, B. R. & Hanson, D. G. (1989) . EEect of superior laryngeai nerve stimulation on phonation in an in vivo canine model. Amencan Journal of Otolamgology, 10. 1 8 1 - 187.
Berry, D. A. , Hemel, H. , Titze, 1. R. & Story, B. H. (1996) . Bifùrcations in excised larynx experiments. J o u d of Voice, 10. 129-128.
Bielamowicz, S. , Berke, G. S. & Gerratt, B. R , (1995) . A cornparison of type 1 thyroplasty and arytenoid adduction. Journa1 of Voice, 9, 466472.
Bielamowicg S. , Berke, G. S. , Watson, D. , Gerratt, B. (1994) . Effects of RLN and SLN stimulation on glottal area. Otolanmaoioav - Head and Neck Surgerv, 1 10,370-380,
Brandenburg, M. D. , Kirkham, W. & Koschkee, D. (1992) . Vocal cord augmentation with autogenous fat. Larvn~osco_~e. 102,495-500.
Bruening, W. (191 1) . Uber eine neue behandlungs methods der rekurrenslahmung. Verh Dtsch Ges Laqmeol. 15 1, 1 8-93.
Coleman, R F. (1993) . Sources of variation in phonetograms. Joumai of Voice, Z, 1-14.
Coleman, R. F. , Mabis, J. H. & Hinson, L K. (1977) . Fundamental frPquency- sound pressure level profiles of adult male and fernale voices. Joumai of S~eech and Hearina Research, 2Q, l97-2O4.
Colton, R. H. & Casper, J. K. (1990) . Understanding voice ~roblerns: a phvsioloeical wrswctive for diamosis and treatment. (199-201) . Baltimore: Williams & Wilkins.
D'Antonio, L. , Wigley, T. L. & Zimmeman, G. J. (1 995) . Quantitative measures of laryngeal îùnction foilowing teflon injection or thyroplasty type 1. Lmg;oscope, 105,256-262.
Dedo, H. H. (1970) . The paralyzed larynx: An electromyographic study in dogs and humans. Larvn~osco~e, 58.1455-1 5 1 7.
Doyle, P. C. , Leeper, H. A. , Houghton-Jones, C - , Hememan, H. & Martin, G. F. (1 996) . Perceptual characteristics of hedaryngectomized and near-total laryngectomized male speakers. Journal of Medical Sbeech-Lannuaee Patholow 1, 131-143.
Fi& B. R. & Demarest, R. J. (1978) . Larvngeal biomechanics. Cambridge, MA: Harvard University.
Fischer, N. D. (1952) . Preliminary report on an application of the motor b c t i o n of the supenor laryngeal nerve. Annals of Otolow. Rhinolow and Larvn~olow, 61,352-353.
Fisher, K. V. & Swank, P. R (1997) . Estimating Phonation Threshold Pressure. Journal of Srnech, Lanwane. and Hearin~; Research, 40.1122-1 129.
Ford, C. , Unger, J., Zundel, R. & Bless, D. (1994) . Magnetic resooance imaging (MRI) assessrnent of vocal fold medialization surgery. NCVS Status and
7 23-27. Promess Reoort, ,
Ford, C. N. , Bless, D. M. & Prehn, R. B., (1992) . Thyroplasty as primary and adj unctive treatment of glottic insufficiency . Journal of Voice, $2770285.
Freedrnan, L. M. (1956) . The role of the cncothyroid muscle in tension of the vocal cords: An experimental study in dogs designed to release tension in vocal
cor& in bilateral recurrent laryngeal nerve paraiysis. The Lanmeoscow, 574-58 1.
Fujimura, O., Hirano, M. (1995) . Vocal fold ~hvsiolonv. Voice W i t v Control. San Diego, California: Singular Publishing Group, Incorporated.
GaufEn, J. & Sundberg, J. (1989) . Spectral correlated of glottal voice source wavefonn characteristics. J o u d of S m c h and Hearinn Disorders, 32. 556-565.
Gardener, G. & Parnes, S. (1 99 1) . Status of the mucosal wave post vocal cord injection versus thyroplasty. Journal of Voice, I, 64-73.
Gelfer, M. P. , Andrews, M. L. & Schmidt, C. P. (1991) . Effects of prolonged loud reading on selected measures of vocal fiinction in trained and untrained singers. Journal of Voice, I, 158- 167.
Gerratt, B. R. , Hanson, D. G. & Berke, G. Glottographic measures of laryngeal h c t i o n in individuals with abnormal motor control. (521-532) . in Vocal fold physiology: Laryngeal fùnction in phonation and respiration. Harris, K., Sasaki, C. , Baer, T. (Eds.) San Diego: Coilege-Hill Press.
Gotaas, C. & Stan; C. D. (1993) . Vocal fatigue among teachers. Folia Phoniatr, 45. 1 20- 1 29.
Gramming, P. (1988) . The ~honetorrram: An emerimental and clinical snidv. M b o , Sweden: Department of Otolaryngology, University of Lund, Malmo General Hospital.
Gramming, P. & Sundberg, J. (1988). . Spectrurn factors relevant to phonetogram measurement. Journal Acoustical Societv of Amenca, 83,23 53 -2360.
Gray, S. D. , Barkmeier, J. , Jones, D. , Titze, 1. & Druker, D. (1992) . Vocal evaluation of thyroplastic surgery in the treatment of unilaterd vocal fold paralysis. Laxyngosco~e. I02,4 1 5-42 1.
Grossmann, M. (1897) . Experimentelle beitrage zur lehre von der "posticuslahmung". Archives of L m e . u Rhinoloev, 6 282.
Hanson, D. G. , Gerratt, B. R. , Berke, G. S. & Karin, R. R (1988) . Glottographic measures of vocal fold vibration: an examination of laryngeal paralysis. Larynnosco~e, a 5 4 1 -549.
Hanson, D. G. (1990) . Phonosurgery: a perspective. (107-124) . h Cummings, C. Fredrickson, J. M. , Harker, L. A. , et. al. , (eds.) Otolaryngology - update II. St. Louis: C. V. Mosby.
Harries, M. L. & Momson, M. (1995) . Short-term r e d t s of laryngeal k e w o r k surgery-thyroplasty type 1: A pilot snidy. The Journal of Otolarvneolonv, 2& 28 1-287.
Herrington-Hail, B. L., Lee, L. , Stemple, J. C., Niemi, K. R, & McHone, M. M. (1 988) . Descriptions of laryngeai pathologies by age, sex and occupation in a treatment seeking sample. Journal of S~eech and Hearing Disorders, 53. 57-64.
Hirano, M. (1981) . Clïnical Examination of Voice. New York: Springer-Verlag Wien.
Hirano, M. & Bless, D. M. (1993) . Videostrobosco~ic examination of the h m . San Diego: Singdar Publishing Group.
Hirano, M., Kirchner, J. A. , Bless, D. M. (1987) . Neurolarvnaolow. Recent advances. San Diego: Singular Publishing Group.
Hoffinan, H. T. & McCuiloch, T. M. , (1996) . Anatomic considerations in the surgical treatment of unilateral laryngeal paralysis. Head Neck 1 8, 1 74- 1 87.
isshiki, N, Tanabe, M. , Ishizaka, K- & Btoad, D. (1977) . Clinical signincance of asyrnmetrical vocal cord tension. Annals of Otolow. Rhînolow and Larvmoloeu, 86.58-66-
Isshiki, N. & Ishikawa, T. (1 976) . Diagnostic value of tomography in unilateral vocal cord paralysis. Larvneosco~e, 86. 1573-1 578.
Isshiki, N. (1998) . Vocal membranes as the basis for phonosurgery. Larpgoscow, 108, 1761-1766.
Issihiki, N. , Okamura, H. & Ishikawa, T. (1975) . Thyroplasty type 1 (lateral compression) for dysphonia due to vocal cord paralysis or atrophy. Acta Otolaryngologica, 80.4650473.
Kamell, M. P. , Titze, 1. R. & Hoffman, H. T. (1997). Longitudinal vocal performance after gortex thyroplasty: A detailed case study. Paper presented at the meeting of the American Speech, Language and Hearing Association.
Kent, R D., Kent, J. F., Rosenbek, J. C. (1987) . Maxium penomance tests of speech production. Journal of Smech and Hearine Disorders, a 367-3 87.
Khidr, A. , Ramos, C. A. , Bless, D. M., & Heisey, D. (1997) Resolvin~ the battle between intemal and extemal for visual ~erce~tual ratinas. Poster presented
at the 1997 Annual Convention of Amencan Speech-Language Hearing Association, Boston, MA.
Kokesh, J. , Robinson, L. R , Flint, P. W. & Cummings, C. H. (1993) . Correlation between stroboscopy and electromyography in laryngeal paraiysis. Annals of Otoloav. Rhinolow and Larvngoloav, 1 02,852-857.
Konrad, H. & Rattenberg, C. C. (1969) . Combined action of laryngeal muscles. Acta Otolarvngoloeica, 67,646449,
Koufinan, J. A. & Winston-Salem, N. C. (1986) . Laryngoplasty for vocal cord medialization: an aitemative to Teflon. Larvnnrosco~e, 96.726-73 1.
LaBlance, G. R. & Maves, M. D. (1992) . Acoustic characteristics of post- thyroplasty patients. Otolaryneolow - Head and Neck Surnerv. 107,558- 563.
Leder, S. B. & Sasaki, C. T. (1994) . Long-term changes in vocal quality following Isshiki thyroplasty type 1. Larvngosco~e, 1 04,275277.
Lieberman, P. (1965) . Some acoustic measures of the bdamentai periodicity of noma1 and pathological larynges. Journal of Acoustic Societv of America, 35,344353,
Lofquist, A. , Carlburg, B. & Kitzing, P. (1 982) . Initiai validation of an indirect measure of subglottic pressure during vowels. Journal of the Acoustical Societv of America, 72,633-635.
Lu, F. , Casiano, R R. , Lundy, D. S. & Xue, J. (1996) . Longitudinal evaluation of vocal îunction after thyroplasty type 1 in the treatment of unilateral vocal paralysis. Larynnoscom. 106,573-577.
Lundy, D. S. & Casiaoo, R R (1995) . ccCompensatory Fdsetto" : Effects on vocal quality. Journal of Voice, 439-442.
Mikaeiian, D. O. , Lowry, L. D. & Sataloff, R. T. (1991) . Lipoinjection for unilateral vocal cord paralysis. Larvneoscotx, 1 0 1,465-468.
Mikus, J. L. , KoufÎnan, L A. & Kilpatrick, S. E. (1995) . Fate of liposuctioned and purified autologous fat injections in the canine vocal fold. Larvnnoscoae, 105, 17-22.
Netsell, R. , Log W. & Shaughnessy, A. L. (1984) . Laryngeal aerodynamics associated with selected voice disorders. American Journai of Otolarvnaoloav, 5.397-403.
Netterville, J. L- , Sone, R E. , Civautos, F. J. , Luken, E. S. & Ossoff, R H. (1993) . Silastic medializattion and arytenoid adduction: the Vanderbilt experience. A review of 1 16 phonosurgical procedures. Annals of Otoloev, Rhinolonv and Larvn~olow. 1 02'4 13-424.
Noordzij, J. P. , Oppennan, D. A., Perrault, D. F. & WOO, P. (1998). The biomechanics of the medialization laryngoplasty (thyroplasty type 1) in an ex vivo canine model. Larvn~oscope, 12.372-382.
Ornori, K. , Slavit, D. H., Kacker, A. & Blaugnind, S. M. (1996). Quantitative criteria for predicting thyroplasty type 1 outcome. Larvn~osco~e, 106,689- 693.
Ornori, K. , Slavit, DI H., Kacker, A. & Btaugrund, S. M. (1996) . Quantitative videostroboscopic measmement of glottal gap and vocal fùnction: An analysis of thyroplasty type 1. Annals of Otolow. Rhuiolonv and Larvngolo~~, 105,280-285.
Parnell, F. W., & Brandenburg, J. H. (1970) . Vocal Cord Paralysis. A Review of 100 Cases. Lary~~~oscom, 80.1036-1 045.
Pemberton, C. , McConnack, P. & Russell, A. (1998) . Have women's voices lowered across tirne? A cross sectional study of Australian women's voices. Journal of Voice, 12,208-2 13.
Ramos Pizarro, CI A- (1998) . Vocal fiuiction measures in premeno~ausal and postmeno~ausai women and their relatioashi~s to sex steroid hormone Ievels. Unpublished dissertation. University of Wisconsin-Madison.
Regenbogen, E. (1989) . Glottal closure in the hemiparaiyzed canine larynx. L a r v n g o ~ c ~ ~ e , 99.71 1-715.
Reynolds, L. V. & Kearns, K. P. (1983) . Single-Subiect Ex~e rhen td Desiai in Communicative Disorders. Baltimore: University Park Press.
Riad, M. A. & Kotby, M. N. (1995) . Mechanism of glottic closure in a model of unilateral vocal fold palsy . Acta Oto larvngologica., 1 1 5 , 3 1 1 -3 1 3.
Sander, E. K. & Ripich, D. E. (1983) . Vocal fatigue. Annals of Otolow. Rhinolow and Larvngology, 92. 141-145.
Sasaki, C. & Harris, K. (eds.) Laryngeal fuoction in phonation and respiration. San Diego: Singular Publishing Group.
Sasaki, C. T. , Leder, S. B. , Petcu, L.& Freidman C. D. (1990) . Longitudinal voice quality changes following Isshiki thyroplasty type 1: the Yale experience. Lat.vn~osco~e. 100,849-852.
Sawashima, M. , Totsuka, G. , Kobayashi, T. , Hirose, H. . (1968) . Surgery for hoarseness due to unilateral vocal cord paralysis. Archives of Otolaryngolow, 87.289-294.
Scherer, R. C. (1 991) . Phonosuraerv: Assessrnent and sureical m e m e n t of voice disorders. (77-93) . Ford, C. N. , Bless, D. M. (eds). Physiology of phonation: A review of basic mechanics. New York: Raven Press Limited,
Scherer, R. C. (1 995) . Laryngeal fûnction during phonation. (86-1 04) In. Rubin, J. S. , Sataloff, R. T. , Korovin, G. S. , Gould, W. J. (eds.) Diagnosis and treatment of voice disorders, New York: Igaku-Shoin Medical Publishers.
Scherer, R. C., Titze, 1. R , Raphael, B. N., Wood R P., Ramig, L. A. & Blager, R F. (1 99 1) . Vocal fatigue in a trained and untrained and an untrained voice user. In: Baer, T. , Sasaki, C. , Harris, K. (eds.) Laryngeal function in phonation and respiration. San Diego: Singular Publishing Group.
Schoenharl, E. (1 960) . Die stroboskopie in der Prakischen Laryngologie, Georg Thieme Verlag: Stuttgart.
Sellars, 1. & Keen, E. (1978) . The anatomy and movement of the cricoarytenoid joint. Larvnrroscom, 88,667-674.
Sercarz, J. A. , Berke, G. S. , Gerratt, B. R , Ming, Y. & Natividad, M. (1992) . Videostrobscopy of human vocal fold paralysis. Annals of Otolonv, RhinoIogv and Larvngolom 101,567-577.
Slavit, D. H. & Maragos, N. E. (1994) . Arytenoid adduction and type 1 thyroplasty in the treatment of aphonia. The~Joumal of Voice, g84-9 1.
Smith, M. E. & Berke, G. S. (1990) . The effects of phonosurgery on laryngeal vibration: Part 1 .Theoretic considerations. Otolar~n~olow - Head and Neck Sur~erv, 103,380-390.
Smith, M. E. , Berke, G. S. & Kreirnan, J. (1992) . Larvnaeal ~aralvses: theoretical considerations and effects on l m e e a l vibration, Journal of Speech and Hearing Research, 3 5,545-554.
Smitheran, J. & Hixon, T. (198 1) . A clinical method for estimating laryngeal ainvay resistance during vowel production. Journal of Srnech and Hearing Disorders, 46. 138-46.
Sonesson, B. (1959) . A method for studying the vibratory movements of the vocal cords. A preliminary report. The Journal of L a m ~ o l o w and Otolofq, a 732-737.
Stemple, J. C. , Stanley, J. & Lee, L. (1995) . Objective masures of voice production in normal subjects foliowing prolonged voice use. J o d of Voice, 9, 127-133.
Stone, R. E. & S M , D. J. (1973) . Vocal change associated with the use of atypical pitch and intensity levels. Folia Phoniatrica, 21,9 1-1 03.
Suzuki, M. , Kirchner, J. A. & Murakami, K. (1970) . The cricothyroid as a respiratory muscle. Its characteristics in bilateral recurrent laryngeal nerve paralysis. Annais of Otolow. Rhinolom and L a r v n e o l o ~ ~ 79.976-983.
Tanabe, M. , fsshiki, N. & Kitajllna, K, (1972) _ Vibratory pattern of the vocal cord in unilateral paraiy sis of the crico thyroid muscle. Acta O t o l ~ ~ o l o &a, 74 339-345. 1
Thompson, D. M. , Maragos, N. E. & Edwards, B. W. (1995) . The study of vocal fold vibratory patterns in patients with unilateral vocal fold paralysis before and after type 1 thyroplasty with or without arytewid adduction. Larvnnoscobe, 1 OS, 48 1 -486.
Titze, 1. R. & Tallcùi, D. 1. (1979) . A theoretical study of the effects of various laryngeal configurations on the acoustics of phonation. Journal of Acoustical Societv of Amenca, 66.60-74.
Titze, 1. R (1973) . The physics of smali-amplitude oscillation of the vocal fol& Journal of the Acoustical Societv of Amenca, 83, 1536-1 552.
Titze, 1. R. (1992) . Acoustic interpretation of the voice range profile (Phonetogram). Journal of Swech and Hearuin Research, 35,21-34.
Titze, 1. R. (1992) . Phonation threshold pressure: A missing Liok in glottal aerodynamics. Journal of Acoustical Societv of Arnerica. 9 1,2926-293 5.
Titze, 1. R. (1994) . Principles of voice production. Paramount Communications Company Engiewood Cliffs, New Jersery: Prentice-Hd , Inc.
Titze, 1. R. , Schmidt, S. S. & Titze, M. R (1994) . Phonation threshold pressure in a physical mode1 of the vocal fold mucosa NCVS Stahis and Promess Remrt, 0, 13-18.
Trapp, T. K. , Berke, G. S., Bell, T. S. , Hanson, D. G. & Ward, P. H. (1989). Effect of vocal fold augmentation of laryngeai vibration in simulated recurrent laryngeal nerve paralysis: A study of teflon and phonogel. Annals of O t o l o ~ ~ , Rhinolow and Larvne;olonv, 98.220-227.
Tucker, H. (1 980) . Vocal cord paraiysis-etiology and management Laryïnosco~e,
Tucker, H. M. , Wanamaker, J. , Trott, M. & Hicks, D. (1993) . Complications of laryngeal b e w o r k surgery @honosurgery) . Larvnnoscow. 103,525-528.
Verdolini-Marston, K., Titze, 1. R. & Druker, D. (1990). Changes in phonation threshold pressure which induced conditions of hydration. Journal of Voice, 4 142-151. 3
Vilkman, E. , Sonninen, A. , Hurme, P. & Korkko, P. (1996) . Extemal laryngeal b e function in voice productio revisited: A review, Journal of Voiice, 78-92.
Von Leden, H. & Moore, P. (1960) . Vibratory pattern of the vocal cor& in unilateral laryngeal paraly sis. Annals of Otoloev. Rhinolonv and Larygnoloav, 53.493-506.
Wagner, R. (1 897) . Die Medianstellung der stimmban der bei der rekurrenslahrnu11g. Archives of Patholonv. Anat.. Ph~sioloal. 120,43749,
Watterson, T. , McFarlane, S. C. & Menicucci, A. L. (1990) . Vibratory characteristics of Teflon-injected and non-hjected paralyzed vocal folds. Journal of S~eech and Hearina Disorders, 55,61-66.
Wilson, J. V. & Leeper, H. A. (1992) . Changes in laryngeal aVway resistance in young adult men and women as a hc t ion of vocal sound pressure level and syllable context. JournaI of Voice, 6 235-245.
Woo, P. , Colton, R. , Brewer, D. & Casper, J. (1991) . Functional staging for vocal cord paralysis. Otolarvneologv - Head and Neck Sureerv. 105,440-448.
Woodson, G. E. (1989) . Effects of recurrent laryngeal nerve transection and vagotomy on respiratory contraction of the cricothyroid muscle. h a l s of Otoloev. Rhinolow and Laryneolopy, 98,373-378.
Woodson, G. E. (1993) . Configuration of the glottis in laryngeal paralysis. iI: Animal experiments. Layneoscow. 1 03, 123 5-1 241.
Woodson, G. E. , Mathew, O. , Sant'Ambrogio, F. & Sant'Ambrogio, G. (1989) . Effects of cricothyroid muscle contraction on laryngeal resistance and giottic area. Annals of Otoloev. Rhinolow and L q n o l o p v , 08, 1 19-123.
Yamanda, M. , Hirano, M. , Ohkubo, H. (1983) . Recurrent laryngeal nerve paralysis. A ten year review of 564 patients. Auris Nasus Larvnx, S 1 S.
Yumoto, E. , Gould, W. & Baer, T. (1982) Hannonics to noise ratios as an index of the degree of hoarseness. Journal of Acoustics Societv of America, 7J 1544-1550.
Zaretsky, L. , Shindo, M. L. , deTar, M. & Rice, D. H. (1995) . Autologous fat injection for vocaI fold paralysis: long term histologie evaluation. Annals of Otoloev. Rhinolom and Laxvnaoloav. 104,l-4.
Zenker, W. (1 964) . Ouestions remdine the function of extemal IarvnPeal muscles.
in: Brewer D. W. (Ed). Research potentials in voice physiology. (20-32) . New York.
Appendix A.
Voice Data Collection Sheet
MPT: AEROPHONE/NAGASHIMA
sec volume ml
sec volume ml
sec volume ml
VOICE SAMPLE Sustained
Fo:/a/ 3 seconds/comforîa bfe level
x Fo: Hz
DATE:
PATIENT NAME:
SMH CEIART #:
BASELINE:
COMFORTABLE FO RANGE: (REAL PITCH : glissande truk)
I
1 ~ntensity 1 Minimum Fo 1 Maximum Fo 1 Rnnge(ST)
SUSTAINABLE Fo RANGE =VRP
Cornfortable t---
Loudest dB SPL Fo W S V
Softest dB SPL
/ /
/ /
/ /
LARYNGEAL AIRFLOW RESISTANCE
Fo Maximum Fo Minimum
PHONATION THRESHOLD PRESSSURE
92 bpm: /pi/ x 7: 3 trains - start sofliy and get. louder
*******WATER BREAK, 10 minute rost, 250 ml of water**.****
READING TASK
75-80dB at (18 inches from SLM) or at subject upper range (5 dB fmm Mnrimum
Iateosity) RECORD MAXIMUM READING TIME (Mio.sec)
Pressure c d 0
Fo Maximum Fo Minimum
Intensity DB SPL
L J
Minutes From Start
MPT (Seconds) V o l u r n ~ S
Appendix B.
Schematic of Medialisation Thpplasty
Note: A. Lateral view of window placed in thyroid cartilage over paralysed vocal fold B. Superior view: Medialisation orparalysed fold by placement of Silastic block
Data Collection Sheet for Effort Rating
Effort Levei: "Rate the amount of effort you think the speaker is required to produce speech."
1. NO 1 2 3 4 5 6 7 8 9 Extreme
Effort Effort
2. No 1 2 3 4 5 6 7 8 9 Extreme
Effort Effort
3. No 1 2 3 4 5 6 7 8 9 Extreme
Effort Effort
4. No 1 2 3 4 5 6 7 8 9 Extreme
Effort Effort
5. No 1 2 3 4 5 6 7 8 9 Extreme
Effort Effort
6. No 1 2 3 4 5 6 7 8 9 Extreme
Effort Effort
Appendix D.
Complete Data for Six Subjects
Trial 1 Trial2 Trial3 MPT(sec) 173 23.12 22.09
Acoustics Fo(Hz) Jitter( %) Sbim (%) Fo 1 274.4 1 8 0.949 3536 Mas Fo2 276351 1.437 4.708 23-12 Fo3 272.974 0337 2.977
Mean 274581 0.974 3.740
Fo Hsbitual(ST) 29 Fo Range Min(ST) Max(ST) Tobl(ST)
t 9 37 18
Fo Min Io Min dB Io Max dB Fo Comf Io Min dB Io Max dB
VRP Arta A 208 B 165 -
Total 373
Ptp/cm H20 Fo Min Io dB FoComf Io dB Fo Max Io dB 1 4.76 65 7.04 82
2 * 3.96 63 6.88 77
3 * I, * 1, 536 77
Mean 436 64 6.43 79 'subject could not complete task
Fo Rigb Io Min dB Io Max dB
Io3 60 86
M u n 63 85
Reading Time Min-sec
Subjcct f Postl
Trial 1 Trial 2 Trial3 Mas MPT(sec) 27.74 28.92 26.1 8 28.92
Acoustics Fo(Hz) Jitîer( 74) Shim (Y.) Fo 1 24 1 -979 0.600 2.010 Fo2 23 1.162 1-171 3.089
Fo Range Mia(ST) Max(ST) TotaYST) 20 3% 18
Fo Min Io Min dB Io Max dB Fo Comf Io Min dB Io Max dB Io 1 52 7 1 Io 1 55 80 Io2 55 70 Io2 54 79 Io3 55 7 1 103 54 79
Mean 54 7 1 Mean 54 79
VRP Area A 332
Ptp/cmHîO Fo Min Io dB Fo Cornf Io dB Fo Max Io dB 1 4.96 63 3.00 6 1 6.16 77 2 4.54 66 2-84 6 1 5.48 76 3 4.68 63 324 65 6.24 77
Mcao 4.73 64 3 .O3 62 5.96 77
Fo High Io Min dB Io Max dB
Reading Timc Min-sec i j
Subjcct 1 POSU
MPT(sec)
Acoustics Fo 1 Fo2 F03 Mean
Fo Habitua1
Fo Range
Fo Min Io 1 Io2 Io3 Mean
VRP Arta
Fo(Hz) Jitter( %) Shim (74) 204292 0.880 5.722 203.909 0565 5.606 203.609 2130 5 -466
Io Min dB Io Max dB Fo Comf Io Min dB Io Max dB 54 68 Io 1 53 79 55 69 Io2 54 78 56 68 103 53 80
- Total 568
Ptp/cmHîO Fo Min Io dB Fo Comf Io dB Fo Max Io dl3 1 4.68 6 1 430 6 1 6.12 72 2 4.20 62 5.08 63 9.96 77
Fo Rïgh Io Min dB lo Max dB Io 1 63 83 Io2 64 85 103 63 84
Mun 63 84
Reading Time Miruec m i
Subject 2 Prcl
Trial 1 Trial2 Trial3 Max MPT(scc) 2-9 1 3-95 2.67 3 -95
Fo Habitua1 25 Fo Range Min(ST) Max(ST) Total(ST)
20 36 16
Fo Min Io Min dB Io Max dB Fo Comf Io Min dB Io Max dB Io 1 57 75 102 58 75 Io3 62 7 1
VRP Area A 149 B 63 -
Total 21 1
Ptp/cmHZO Fo Min Io dB Fo Comf Io dB Fo Max Io dB
'Subject could not wmplete task (los of phonation)
Fo High Io Min dB Io Max dB Io 1 62 74 102 62 75 103 63 73
Mean 62 74
Reading TIme Min.sec
Subject 2 Postl
MPT(sec)
Acoustics Fo 1 Fo2 Fo3
Mean
Fo Habitua1 Fo Range
Fo Min Io 1 Io2 103
Mean
VRP Area
Io Min dB Io Max dB FoComf Io MindB Io MaxdB 62 75 Io 1 63 86 65 7 1 Io2 63 85 64 73 Io3 63 84 -
64 73 Mean 63 85
A 165 B 31 -
Total 196
Ptpkm HZ0 Fo Min Io dB Fo Comf IodB Fo Max IodB
Fo Righ Io Min dB Io Max dB
Reading Time Min-sec -1
Subject 3 Prel
Trial 1 Trial 2 Trial 3 Max MPT(sec) 4.4 1 5-18 435 5.18
Acoustics Fo(Hz) litter( O!) Sbim (94) Fo 1 171.415 *22.103 *38313 Fo2 189.410 3.153 9.698 Fo3 187.907 4.925 7,173
Mean 182.9 1 1 4.039 8.436
Fo Range Mia(ST) Max(ST) Toîal(ST) 18 24 6
Fo Min IO Min dB Io Max dB Fo Comf Io Min dB Io Max dB Io 1 5 8 62 10 1 55 70 Io2 58 61 102 56 72 Io3 5 8 60 103 56 70 Mean 58 6 1 Mean 56 7 1
VRP Area
B 36 - Total 59
Ptp/cmH20 Fo Min Io dB Fo Comf IodB Fo Max Io dB
1 3.64 5 8 3 -44 54 328 6 1 2 4.08 6 1 3 -72 62 3.68 57 3 4.04 62 2.84 5 7 339 62
Mean 3.92 60 3.33 5 8 3.45 60
Fo High Io Min dB Io Max dB Io 1 58 66 102 60 67 Io3 60 67
Mean 59 67
Reading Tirne Minsec
Subject 3 Pr&
M m s e c )
Acoustics Fo 1 Fo2 Fo3
Mean
Fo Habitua1
Fo Range
Fo Min Io 1 102 Io3
Mean
VRP Area
Trial 1 Trial 2 Trial 3 Max 3 -80 3 -64 3 -89 3.89
Fo(H2) Jitter( Ym) Sbim (Y.) 188.802 5.464 7-464 189374 3.112 9.676 187.438 5.099 6322
188.538 4558 7.82 1
Io Min dB Io Max dB 5 5 67 5 7 65 57 62
56 65
Fo Coml Io Min dB Io Max dB Io 1 57 70 102 59 69 Io3 60 68
Mean 59 69
- Total 56
PtpkmHîO Fo Min Io dB Fo Comf IodB Fo Max IodB
Fo Efigb Io Min dB Co Max dB Io 1 57 69 Io2 6 1 67 Io3 62 69
Mean 60 68
Reading Time Min.sec pq
Subject 3 Postl
Trial 1 Trial 2 Trial 3 Max MPT(sec) 8.70 8.60 639 8.70
Acoustics Fo(H2) Jitter( %) Shim (%) Fo 1 199.089 4.146 8386 Fo2 212327 3.101 7.679 Fo3 223.402 3.666 6.952
- Mean 2 1 1 -606 3.638 7.672
Fo Range hiin(ST) Max(ST) Totat(ST) 23 33 1 O
Fo Min Io Min dB Io Max dB Fo Comf Io Min dB Io Max dB Io 1 57 74 Io2 59 72 Io3 54 73
Mcan 57 73
W Area A 92 B 34 -
Total 126
Ptp/cmHiO Fo Min Io dB Fo Comf Io dB Fo Max Io dB
Fo High Io Min dB Io Max dB Io 1 6 1 70 Io2 65 69 Io3 67 74
Meaa 64 7 1
Reading Time Minsec
Subjcct 3 PostZ
MPT(scc)
Acoustics
Fo 1 Fo2 Fo3
Mean
Fo Habitua1
Fo Range
Fo Min Io 1 Io3 Io3
Mean
VRP Arta
Trial 1 Trial2 Trial3 hfru 13.72 10.47 10.19 13.72
Io Min dB Io Max dB 6 1 67 60 68 59 67
Fo Comf Io Min dB Io Max dB Io 1 60 75 Io2 58 76 Io3 60 74
Mean 59 75
- Total 206
Ptp/cmH20 Fo Min Io dB Fo Comf Io dB Fo Max IodB 1 4.08 63 2-88 5 9 6.00 66 2 336 59 2.40 53 6 -64 66 3 3.00 60 2.76 58 4.76 6 1
iMean 3.48 6 1 2.68 57 5.80 64
Drïfüng Intensity for 1st and 2nd ptp at Fo min
Fo High Io Min dB Io Max dB Io 1 62 77 102 62 78 103 60 79
Mean 6 1 78
Reading Time Min-sec
Subject 4 Prel
Trial 1 Trial 2 Trial 3 Max MPT(sec) 8.88 9.14 924 9 2 4
Acousties Fo 1 Fo2 Fo3 Mean
Fo Habituai Fo Range
Fo Min Io f 102 Io3
Mean
VRP Area
Fo@z) Jitttr( %) Sbim (%) 148.786 6.760 8.180 144.889 7243 11.296 149.708 4.049 6.419 147.794 6.017 8.632
Io Min dB Io Max dB Fo Comf Io Min dB Io Max dB 5 7 62 10 1 52 63 54 65 102 56 64 5 5 62 103 59 66 55 63 Mean 56 64
-
Total 224
PtpkmH20 Fo Min Io dB Fo Comf Io dB Fo Max IodB 1 1.88 57 5.80 60 2 324 57 5.72 59 3 . 3 -64 59 4.04 59
Mean 2.92 58 5.19 59
*Lowest sustainable was 03 , same as cornfortable Fo
Fo Higb Io Min dB Io Max d8 Io 1 57 70 Io2 50 74 Io3 52 72
Mtrn 53 72
Reading Time Minsec
Subject 4 Pm2
MPT (sec)
Acoustics Fo 1 Fo2 Fo3 Mean
Fo Range
Fo Min 101 102 103 Mean
Ptp/cmH20
Mean
Reading Time
Trial 1 Trial2 Th13 Max 9.0 1 8.21 9.67 9.67
Fo(Hz) Jitter( ./) Shim (*A) 146.210 4.631 7.115 149.713 4.019 6372
Io Min dB Io Max dB Fo Comf Io Min dB Io Max dB 54 63 Io 1 56 68 5 5 64 Io2 54 70 54 64 Io3 52 67 54 64 Mean 54 68
Fo Min Io dB Fo Comf lodB Fo Max IodB 1 3 -40 57 6.40 59
2 * 3 -84 58 5.40 60 3 3 -60 59 4.52 58
3.6 1 58 5.44 5 8 *Subject could sustain D3 *Lowest sustainable D3 (habituai)
Fo Eigb Io Min dB Io Max dB Io 1 56 70 Io2 57 70 103 56 70
Mean 56 70
* * Hyperventilation
Subject 4 Postl
M PT(sec)
Acoustics Fo 1 Fo2 Fo3 Mean
Fo Habitua1
Fo Range
Fo Min Io 1 Io2 Io3 Mean
T h 1 1 Trial2 Trial3 Max 16.42 14.73 12.98 16.42
*23 *subject rernaind at G3 for VRP intensity despite the vowel tokms at 21 and 22 ST
Io Min dB Io Max dB Fo Comf Io Min dB Io Max dB 54 58 Io 1 6 1 75 5 5 6 1 Io2 56 75
Ptp/cmH20 Fo Min Io dB Fo Comf Io dB Fo Max Io dB 1 4.76 57 4.04 69 5.72 67 2 4.12 68 3.84 66 4.04 67 3 4.56 6 I 4.00 67 6.44 70
Mean 4.48 62 3 -96 67 5 -40 6 8
Fo High Io Min dB lo Max dB Io 1 57 85 Io2 57 85
Reading Time Min.sec pq
Subject 4 Post2
MPT(sec)
Acoustics Fo 1 Fo2 Fo3 Mean
Fo Range
Fo Min Io 1 Io2 Io3 Mean
PtpIcmHZO
~Meao
Trial 1 Trial 2 Tria13 Max 14.04 12.8 8 13.08 14.04
Io Min dB Io Max dB Fo Comf Io Min dB Io Max dB 56 66 lo 1 56 7 1 54 66 Io2 5 7 70 57 66 Io3 55 70
Fo Min Io dB Fo Comf Io dB Fo Max IodB 1 4-00 65 320 58 4.88 54 2 4.56 56 3.68 60 4-56 60 3 3.44 58 3 -60 57 5-20 57
4.00 60 3 -49 58 4.88 57
Fo Higb Io Min dE3 Io Max dB Io 1 54 80 102 57 87 103 57 87
Meaa 56 85
Reading Time Min.sec
m
Voicc R.mge Pmfik W Port 1 j
Voico Rang. ProVik LI P m
Subject 5 Prcl
Trial 1 Trial2 Trial3 M u MPT(sec) 11.01 9.27 937 11.01
Acoustics Fo 1 F02 F03 Mean
Fo Eiabitual
Fo Range
Fo Min Io 1 102 Io3 Mea n
VRP Area
Fo(Hz) Jittrr( %) Sbim (95) 16 1.039 2.724 5-151 163.508 0.644 3.66
Io Min dB Io Max dB Fo Comf 10 Min dB Io Max dB 58 6 1 Io 1 62 82 55 6 1 102 59 80
B 104 - Totd 404
PtpfcmH20 Fo Min Io dB Fo Comf Io dB Fo Max Io dB 1 2 2 8 56 3 .O0 64 9.92 87 2 2.42 56 3 .O8 65 7.12 87
Fo High Io Min dB Io Max dB Io 1 68 80 Io2 70 92 103 68 9 1 Man 69 88
Reading Time M i m c 1-1
Subjcct 5 f r d
Trial 1 Trial2 Trial3 M u MPT (sec) 10.95 12.73 12-20 12.73
Acowtics Fo(H2) Jittcr( %) Shim (%) Fo 1 149.5 19 0.502 26% F02 146.220 0.414 237 F03 146.694 0386 2-259 Mcan 147-478 0.434 2.408
F o Habitual (ST 18
Fo Range Min(ST) Max(ST) TotrI(!Fï) 15 33 18
Fo Min Io Min dB Io Max dB Io 1 59 63 Io2 56 63
Fo Comf Io Min dB Io Max dB Io I 65 76 Io2 63 74
VRP Area A 165
PtplcmH20 Fo Min IodB Fo Comf Io dB Fo Max Io& 1 3.12 58 3.04 65 7.52 84 2 3.6 59 3.12 67 7.52 79
Fo Higb Io Mi dB Io Max dB Io 1 70 80 Io2 74 85
Reading Time Mhsec rn
Subject 5 Postl
Trial 1 Trial2 Trial3 hfar MPT(scc) 13.79 13.76 13-82 13.82
Acoustics Fo(Hz) Jiîîcr( %) Shim (?A) Fo 1 135.007 O552 3.863 Fo2 135.832 0320 2,927
Fo Range iMin(W Max(ST) Totril(!Sï) 11 39 28
Fo Min Io Min dB 10 Max dB Io 1 59 70 Io2 60 68 Io3 60 68 Mean 60 69
FoComf IoMindB IoMaxdB Io 1 54 74 Io2 57 78 Io3 55 78
Mcan 55 77
VRP Area A 368 B 78 -
Total 446
PtpfcmHZO Fo Min Io dB FoComf Io dB Fo Max Io dB 1 4,I2 62 1.68 6 1 7.60 '81 2 3.88 62 2.64 58 9.60 77
Fo High Io Min dB 10 Max dB Io 1 78 88 102 78 89 103 80 89
M u n 79 89
Reading Time Minsec 1 20.00 1
Subject 5 Posa
Acoustics Fo(Hz) T i r ( %) Sbim ( O ! )
Fo : 126.280 0.595 5-985 Fo2 129.88 1 0.627 7-103 Fo3 136360 0302 3.559
= Mcan 130.840 0508 5.549
Fo Min Io Min dB Io Max dB Fo Comf Io Min dB Io Max dB Io 1 59 68 Io l 6 1 74 Io2 58 68 102 58 76 Io3 56 67 103 58 75
Meao 58 68 Mean 59 75
VRP A n a
B 65 - Total 450
Ptp/crnH20 Fo Min Io dB Fo Comf Io dB Fo Max Io dB 1 3.12 60 3.60 62 7.92 77 2 3.56 56 2.68 6 1 928 79 3 2.96 5 1 2.92 6 1 '7.76 *8 1
Mean 3.21 56 3 .O7 6 1 8.60 78
Fo Higb Io Min dB Io Max dB Io 1 74 97 102 78 % Io3 79 %
Meao 77 96
Intensity peaked
Reading Time Mhsec
Subjcct 6 Pm1
kIPT (sec)
Aco w tics Fo 1 F02 F03 Mcan
Fo Habitua1
Fo Range
Fo Min Io 1 Io2 103 iMcan
VRP Area
Trial 1 Trial2 Trial3 Mas 9.47 10.95 932 10.95
Fo(Hz) Jittcr( 76) Sbim (%) 198.439 2597 3207 206.606 0.77 1 1.747 f96.483 3.158 3345 200.509 2175 2.766
Io Min dB Io Max dB Fo Comf Io Min dB Io Max dB 56 60 Io I 55 67 57 63 Io2 55 69 57 6 1 103 54 7 1 5 7 6 1 Mcan 55 69
Ptp/cmLf20 Fo Min Io dB Fo Comf Io dB Fo Mau Io dB 1 3.12 58 3.84 OS 728 76 2 3.20 6 1 3.96 65 820 79 3 3.72 57 4-52 69 9.08 8 1
Mcan 3.35 59 4.1 1 66 8.19 79
Fo Aiih Io Min dB O Max dB io 1 64 92 102 62 94 103 64 % Mun 63 94
Reading Tirne Minsec p z q
Subject 6 P d
Trial 1 TriPl2 Trial3 Max MPT(scc) 1033 9.86 8.55 1033
Acoustiu F e ) Jitter( %) Sbim (54) Fo 1 221.588 2.532 3203 Fo2 217.565 1.994 2349 F03 209.723 2,776 2519 Mean 216.292 2.434 2657
Fo Range Min(Sf) Max(ST) TotaYST) 19 45 26
Fo min IO Min dB Io Max dB Fo Camf Io Min dB Io Max dB Io 1 56 67 Io l 54 78 r02 55 67 102 54 80
VRP Area A 440 B 114
Total 554
Ptp/cmH20 Fo Min Io dB Fo Comf Io & Fo Max Io dB 1 3.56 57 6.64 66 13.76 8 1 2 3.52 60 5.84 67 1232 78 3 4.08 6 1 736 68 12-56 77
Mean 3 -72 59 6.6 1 67 12.88 79
Fo Aigb Io Min dB Io Max dB Io 1 76 92 Io2 77 95 103 77 98 M u n 77 95
Reading Time Min-sec r-1
Subjcct 6 Postl
=(=)
Acoustics Fo 1 Fo2 F03 Mean
Fo Habitua1
Fo fbngc
Fo Min Io 1 Io2 Io3 hlean
VRP Area
Trial 1 Trial2 Trial3 Mir !a34 2028 18-41 2028
Fflz) Jittcr( %) Sbim (9%) 208.422 4,003 2608 199.959 2849 3.172 213333 1.793 2277 207.238 2882 2686
Io Min dB Io Max dB Fo Coml Io Min dB Io Max dB 54 72 Io 1 52 79 56 67 Io2 53 79 55 67 Io3 53 80 55 69 Mean 53 79
A 588 B 100
Total 688
Ptp/cmHZO Fo Min Io dB Fo Comf Io dB Fo Max Io dB 1 3.16 60 2.88 59 3.52 77 2 4.08 62 3.44 63 536 73 3 3.84 58 2.56 63 6.16 76
a Mean 3.69 60 2.96 62 5.0 1 75
Fo Higb Io Min dB Io Max dB Io 1 68 89 102 66 97
Subjcct 6 Posa
MPT (sec)
Acoustics Fo 1 Fo2 Fo3 Mtan
Fo Habitua1
Fo Range
Fo Min Io 1 102 Io3 Meaa
VRP Area
Trial 1 Trial2 Trial3 Max 18.00 17.54 19.09 19.09
Io Min dB Io M a dB Fo C o d Io Min dB Io Max dB 54 69 10 1 56 77 53 70 102 57 77 54 73 Io3 57 76 54 7 1 Mcan 57 77
- Total 702
Ptp/crnH20 Fo Min Io dB Fo Comf 10 dB Fo Max Io dB 1 5.92 55 2.18 64 8-04 75 2 5.16 67 2.40 64 6.24 79
Fo Hïgb Io Min dl3 Io Max dB Io 1 66 99 102 63 99
Reading T i e Min-sec
Appendix E.
Examp1es of Phonation Threshold Pressure
Iniraoral Pressure
............. I r :
Note: Sirnultaneous r&ordïng of intensity, subglottic pressure and airflow. Point A (77dB): First intensity deflection represents onset of phonation Point B (7.92 cmH20): First intraorai pressure peak preceding the intensity deflection Point C (O Litreslsecond): No airflow during pressure peak of bilabial consonant Point D: A low level intensity tracing indicates ody noise fiom airftow without the omet of phonation
Intensity
Intraoral Pressure
............................ LN- 1
Note: Intensity fluctuated &er onset of phonation, therefore the level was chosen at a stable portion of the vowel Point A (65d.B): First sharp rise in intensity level indicating onset o f phonation Point B (3.84 cm&O): Intraoral pressure peak preceding onset of phonation Point C: No airfiow (O Litredsecond) during bilabial consonant (Data fiom Subject 6)
Date: t0 1
10: ST. MICHAEL'S HOSPtTAL, TORONTO, ONTARIO
Consent Form - S PM H Consent lo Dlapnoslic. Opeiaave sr MICHAECS HOSPITAL or Treatment Procedures .
1, hereby consent to the following diagnostic, operative or Nam Or PIWU
treatment procedure(s): 1
to be perforrned upon by Doctor(s)
P&t,n( io.
I The anticipated nature. effect and therapeutic allemat~vet of such procedures have been expiarned to me. i
;
The risks of these procedures have been explained to me and I confirm that l understand and am satisfied with 1 the explanations about the nature. effect and fisks of the procedure(s) that will be performcd upon me.
I consent to ail preliminary and related procedures and to the administration of general andlof other anaefthetics and to such additional or alternative grocdures as may be necessary or medicaily advisable during the course of the above procedure(s).
I understand that St. Michaers Hospital is a teaching hospital and that various medical care personnel may k involved in these procedures.
Tissue rernoved for diagnostic or therapeutic purposes may aftenivards be used for medical education andlor scientific research.
This consent is moâified as follows:
-
I declare that f have raid the above consent to surgical operation, diagnostic test or medical treatment or it has been read and oxplained to ma and I fully understand the rame.
Nam, d Scaond HDtnrs - Pirrw Pmt
If Interpreter Used: ( 1
M a r of Incarglemr - PI IU I Ofun T « . ~ N ~
1 Consent A
Consent Form - Thyroplwty Shidy
Voice Characteristics of Patients with Uniiateral V o d Cord ParaiysW
You are requested to take part in a research study of the voice characteristics of patients with paralysis of one vocal cord Your participation is entirely voluntary and in no way & i l the quaiity of care at this institution now or in the fiture.
Purpose
The purpose of this study is to objectively describe the voice characteristics of patients with paralysis of one vocal cord for at least six months duration but Iess than two years. Changes in voice characteristics afier a rehabiiitative procedure (thyroplasty) will also be documente&
What is the Examination for the study?
The examination consists of a consultation with the surgeon regarding the vocal cord paralysis and initial videotape examination of the voice box. This indicates the position of the vocal cords during speech. A separate voice recording session will take place in the Voice Laboratory. The patients will be requested to use their voice during different pitch and loudness levels. A mask is used to record airflow during voice tasks. A reading task is also tape-recorded for a maximum of 20 minutes. This session usudy lasts 1 to 1- 1/2 hours. The same examination will take place one month and three months after the thyroplasty procedure to document the ciifference in voice characteristics.
Risks of the Study
The videotape examination of the vocal cords is a normal part of the pre-operative planning by the surgeon. The voice tasks are aiso part of an evaluation of voice quality normally done as part of treatment for voice disorders by a speech language pathalogist. There is no risk to the vocal structures as a result of the voice data collection. It is possible some d d temporary vocal fatigue could occut after the study session with no risk of long-tenn effects. The surgery performed is not altered as a result of the study protocol.
Study Records
Al1 records are confidential and are kept by the p ~ c i p a l investigator although they may be used for future publication. The Voice Laboratory at St Michael's Hospital will also keep records.
Questions
Please ask any questions on any aspects of this study that is unclear to you before signing the consent form. Participation is entirely voluntary and in no way affects your care.
Appendix G.
Copyright Permission
Tuesday, Mach, 16,1999
Dr. Dominique Dorion Editor, ORL Publications ihe Journal of Otolaryngology Faculte de Medecine 300 1 1 26 Ave. Nord Sherbrooke, Quebec J1H 5N4
-. Oear B. Donorr:
I am reqwsüng permission to repmduce figure 1 ubyngeal Scorlng System" hm ywr artide 'Short-terni results of layngeai f r a m e w surgery-thyropbsty type 1: A pikt studf m i n e by H a m , M. 1. . MO&UI, M. (1 995)
I would Eke lo use thït informaibn as a ceference kr my Masler of Sàem m i s , Univeaily of T m t o .
I would appreciate hearirg fmm p.
Thank you kindty.
~l$ryqology - Head & Ne* Surgefy
JAAt
Toronto's Urban Angel
Appeadix H.
Tenns and Abbreviations
CT
dB
Fo
1
LCA
MPT
PCA
PTP
RLN
SLN
TA
VRP
Abbreviations
cricothyroid muscle
decibel
fiuidarnental kquency
intensity
lateral cncoarytenoid muscle
maximum phonation t h e
posterior cricoarytenoid muscle
phonation threshold pressure
recurrent laryngeal nerve
superior Iaryngeal nerve
thyroarytenoid muscle
voice range profile
Tenns
Falsetto
A section of the vocal range where the voice is perceived to be
continuous but weak in timbre and usually a high pitch level (Fujimura
& Hirano, 1995).
Glottal Fry
A section of vocal range where the voice is perceive to be pulsed and
temporal gaps are noted @ujimura and Hirano, 1995).
Modal register
A section of vocal range where the voice is perceived to be continuous
and rich in timbre (Fujimura & Hirano, 1995).
