Revue canadienne d’audition · 2016-03-24 · I really didn’t know (and indeed indicated this...

Vol. 7 No. 52012

Publications Agreement Number 40025049 | ISSN 1718 1860

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OFFICIAL PUBLICATION OF THE CANADIAN ACADEMY OF AUDIOLOGYPUBLICATION OFFICIELLE DE L’ACADÉMIE CANADIENNE D’AUDIOLOGIE

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Centring Surprises in Asymmetrical Listeners

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Irecently received agreat honour. I was

informed that I wasbeing audited by myprovincial governmentprogram for prescribingtoo many binauralhearing aids, and thatthis was “way above therate of binaural hearing

aid prescription by my colleagues.”Although this did take a fair amount ofpaperwork and the pulling of almost 200files it did give me the opportunity toperform a self-review, and this is always agood thing. In fact, many provincialcolleges that regulate the profession ofaudiology do just this, and I have alwaysfound this to be a constructive and oftenenlightening endeavour.

Of the 193 files pulled, indeed the vastmajority were for binaural fittings. Therewere 6 that were “suspect” in the sense thatI really didn’t know (and indeed indicatedthis on the hearing aid evaluation form)whether they would benefit from twohearing aids instead of one. My clinicalintuition was “let’s try it and you alwayshave the option of returning one, or both,at the end of a trial period.” We can onlypredict so much in our clinics. The hearingaid wearer just needs to wear it outside andexperience amplified life for several weeks.

Several issues ago, in the Canadian HearingReport, Dr. Wayne Staab was graciousenough to give his perspective on the moregeneral question of “what percentage ofpeople who need hearing aids, actually getthem.” His response was based on theconcept of “hurt.” Was a person botheredby their hearing loss and is this not fullypredictable from their audiometricmeasurement? Dr. Staab, and indeed mostof the clinicians I know, stated that it wasfine to recommend amplification forsomeone who had near normalaudiometric thresholds, if they experiencedcommunication difficulty, especially inadverse listening environments. Thisdiscussion can be extended further to thefitting of binaural hearing aids – I wouldargue that a binaural fitting is best unless

it’s not. And the way we know that it’s “not”is because the hearing aid wearer feels thatthere is no benefit from having the hearingaid(s) after trying it in real life enviro-nments.

Audiometry is such a gross and simplisticmeasure yet we rely on it to such a greatextent. With the advent of other tests thatpurport to assess audiometric function,rather than audiometric sensitivity, we aregaining a new appreciation of how to dealwith our hard of hearing clients. Forexample, otoacoustic emission measuresbecome pathological long before oneobserves and audiometric pure tonethreshold shift. In some sense, by the timethat one observes a measureable hearingloss using pure tone threshold testing, a lotof cochlear damage has already occurred.And with long standing cochlear damagewe are now seeing more central changesthat diminishes an individual’scommunication ability.

So, should our clinical decision torecommend one, two, or no hearing aidsbe based on audiometric pure tonethresholds – probably not, but more oftenthan not, regulators have nothing more togo on. It is of course more complex thanthis. For example, is a fitting of two hearingaids a truly binaural fitting or are theremore central processing issues that limitthe full benefit of binaural summation,phase integration, and synthesis? It istherefore our responsibility as a professionto update our regulators (who have adifficult enough job as is) with currenttechnology, assessment techniques, andclinical philosophy. Preferred PracticeGuidelines (or PPGs) are statements ofminimal care. Perhaps it’s time to have“Optimal Practice Guidelines” as well?

In this issue of the Canadian Hearing Reportwe are pleased to present you with anarticle by Christopher Schweitzer andChristopher McCarron about someinteresting phenomena with asymmetricallisteners that touch on some of these issues.Alberto Behar, in his column Noise aboutNoise questions the usefulness ofaudiometric testing, and some of the issues

surrounding this. And Calvin Staples inFrom the Blogs has selected several blogentries from HearingHealthMatters.orgabout issues surrounding ethics.

Peter Stelmacovich, in his column TheDeafened Audiologist continues with thetheme that more may be better. Weshouldn’t restrict what we are able to offerour clients and this includes directionalmicrophones, wireless options, and the useof assistive listening devices such as FMsystems – more may be better. For any oneclient, this may not be the case, but unlessthey are provided with the opportunity toexperience the options that our field canoffer, there is no way of predicting whorequires what in an apriori fashion.

Gael Hannan continues with the HappyHoH and talks about the many things thata hard of hearing person needs to worryabout. And in this issue we have a guestcolumnist for All Things Central – IreneHoshko discussed central auditoryprocessing assessment with children in2012 and where we are now. In Spotlighton Science Lendra Friesen and SamidhaJoglekar update us on the Oral vs.Intratympanic Steroid Treatment forSudden Sensorineural Hearing Loss. Fromtime to time we see clients who wake upwith a sudden, unexplained unilateralhearing loss (or even a suddenly deafenedclient – both of whom stretch our clinicaland counselling experience. This is a niceoverview of the current state of affairs andwhat we should be telling our clients.

There is a lot to think about in this issue ofthe Canadian Hearing Report – somethingto cuddle up with in front of a roaring fire,or at least a fluffy armchair. I hope you areenjoying your fall, and for those of youwhom attended the past CanadianAcademy of Audiology convention inOttawa, I hope you also enjoyed meetingnew colleagues and re-connecting with oldclassmates.

Marshall Chasin, AuD, M.Sc., Aud(C), Reg.CASLPO, [email protected] Hearing Report 2012;7(5):3-4.

Message froM the editor-in-Chief |

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Official publication of the Canadian Academy of Audiology

Publication officielle de l’académie canadienne d’audiologie

www.canadianaudiology.caEDITOR- IN-CHIEF / ÉDITEUR EN CHEF

Marshall Chasin, AuD., MSc, Reg. CASLPO, Director of Research, Musicians’ Clinics of Canada

ASSOCIATE EDITORS / ÉDITEURS ADJOINTS

Alberto Behar, PEng, Ryerson University

Leonard Cornelisse, MSc, Unitron Hearing

Joanne DeLuzio, PhD, University of Toronto

Lendra Friesen, PhD, Sunnybrook Health Sciences Centre

Bill Hodgetts, PhD, University of Alberta

Lorienne Jenstad, PhD, University of British Columbia

André Marcoux, PhD, University of Ottawa

MANAGING EDITOR / DIRECTEUR DE LA RÉDACTION

Scott Bryant, [email protected]

CONTRIBUTORS

ART DIRECTOR/DES IGN / DIRECTEUR ART IST IQUE/DES IGN

Andrea Brierley, [email protected]

SALES AND CIRCULATION COORDINATOR. /COORDONATRICE DES VENTES ET DE LA DIFFUSION

Brenda Robinson, [email protected]

ACCOUNTING / COMPTAB IL ITÉ

Susan McClungGROUP PUBL I SHER / CHEF DE LA DIRECT ION

John D. Birkby, [email protected]____________

Canadian Hearing Report is published six times annually by Andrew JohnPublishing Inc. with offices at 115 King Street West, Dundas, On, CanadaL9H 1V1.

We welcome editorial submissions but cannot assume responsibility orcommitment for unsolicited material. Any editorial material, including pho-tographs that are accepted from an unsolicited contributor, will becomethe property of Andrew John Publishing Inc.

FEEDBACKWe welcome your views and comments. Please send them to AndrewJohn Publishing Inc., 115 King Street West, Dundas, ON, Canada L9H 1V1.Copyright 2012 by Andrew John Publishing Inc. All rights reserved.Reprinting in part or in whole is forbidden without express written con-sent from the publisher.

INDIVIDUAL COPIESIndividual copies may be purchased for a price of $19.95 Canadian. Bulkorders may be purchased at a discounted price with a minimum order of25 copies. Please contact Ms. Brenda Robinson at (905) 628-4309 [email protected] for more information and specificpricing.

Revue canadienne d’audition_______________________

Vol. 7 No 5 • 201237

Vol. 7 No 5 2012 |

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Calvin Staples, MSc, Conestoga College

Rich Tyler, PhD, University of Iowa

Michael Valente, PhD, Washington University

Kim L. Tillery, PhD, State University of New York, at Fredonia

Publications Agreement Number 40025049 • ISSN 1718 1860

Return undeliverable Canadian Addresses to:Andrew John Publishing Inc. 115 King Street West, Dundas, ON, Canada L9H 1V1

Alberto Behar, Marshall Chasin, Lendra Friesen, Gael Hannan, Neil Hockley, Irene Hoshko, Samiihda Joglekar, Christopher McCarron,

Christopher Schweitzer, Calvin Staples, Peter Stelmacovic

DEPARTMENTS

Message from the Editor-in-Chief Message du L’editeur en chef

COLUMNS

FROM THE [email protected] CALVIN STAPLES, MSC

ALL THINGS CENTRALPediatric (Central) Auditory Processing Assessment In 2012: Where Are We?BY IRENE M. HOSHKO, M.SC.(A) AUD(C) OOAQ

THE HAPPY HOHThe Hearing Loss Worry-WartBY GAEL HANNAN

THE DEAFENED AUDIOLOGISTHearing Loss from Both Sides of theSound Proof BoothBY PETER STELMACOVICH

SPOTLIGHT ON SCIENCEOral vs. Intratympanic Steroid Treatment for Sudden Sensorineural Hearing Loss (SSNHL): Important Information for the Clinical AudiologistBY LENDRA FRIESEN PHD, AND

SAMIDHA JOGLEKAR, MCLSC (C), AUDIOLOGIST,

REG. CASLPO

contents

Gael Hannan, Hearing Loss Advocate

Sheila Moodie, PhD, University of Western Ontario

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COLUMNS

NEW ON THE SHELVES

FROM THE DUSTY BOOKSHELVESAcoustical Factors Affecting Hearing Aid Performance: A Retrospective ReviewREVIEWED BY NEIL S. HOCKLEY, MSC, AUD(C)

FROM THE LIBRARYHearing Aids by Harvey DillonREVIEW BY MARSHALL CHASIN, AUD, AUDIOLOGIST

THE NOISE ABOUT NOISEIs Audiometric Testing Necessary?BY ALBERTO BEHAR, PENG, CIH

FEATURES

RESEARCH AND DEVELOPMENT FOCUSAuditory Brainstem Response and the Travelling Wave DelayBY LAURA PRIGGE, AUD, SHERRIE WELLER,

AND LYNN WEATHERBY

Centring Surprises in Asymmetrical ListenersBY H. CHRISTOPHER SCHWEITZER, PHD

AND CHRISTOPHER MCCARRON, AUD

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Message du L’editeur en Chef |


J’ai récemment reçuun grand honneur.

On m’a informé queje faisais l’objet d’unevérification par leprogramme du gouv-ernement provincialpour avoir prescrisbeaucoup d’appareils

auditifs binauraux, ce qui était “ bien au-delà du taux des prescriptions desappareils auditifs binauraux de mescollègues.” Même si ça a pris un tempsappréciable et l’extraction de presque200 dossiers, ceci m’a donnél’opportunité de procéder à une auto-révision, ce qui est toujours une bonnechose. En fait, plusieurs collègesprovinciaux qui règlementent laprofession de l’audiologie font justementça, ce que j’ai toujours trouvé trèsconstructif et souvent un effortinstructif.

Des 193 dossiers tirés, à ne pas endouter, la vaste majorité étaient pour desajustements binauraux. 6 d’entre euxétaient “suspect” dans le sens queréellement je ne savais pas (et en faitindiqué dans le formulaire dévaluationde l’appareil auditif) si la personne allaitbénéficier de deux appareils auditifs aulieu d’un seul. Mon intuition cliniqueétait “on va l’essayer et vous aveztoujours l’option de restituer un ou lesdeux, à la fin de la période d’essai.”Nous ne pouvons pas tout prédire dansnos cabinets. Le porteur de l’appareilauditif a juste besoin de le porter àl’extérieur et faire l’expérience de la vieamplifiée pendant quelques semaines.

Dans des numéros précédents de larevue canadienne d’audition, Dr WayneStaab nous avaient donné sa perspectiveautour de la question plus générale “despersonnes qui ont besoin d’appareilsauditifs, quel pourcentage d’entre elles

effectivement les obtiennent.” Saréponse était basée sur le concept de“préjudice.” Est-ce que la personne étaitdérangée par sa perte auditive et quececi ne serait prévisible si on regarde deprès ses mesures audiométriques ? Dr.Staab, et en fait la plupart des cliniciensque je connaisse, ont déclaré que c’étaitnormal de recommander l’amplificationà quelqu’un dont les seuilsaudiométriques étaient normaux, s’il ades difficultés de communications,spécialement dans des environnementsd’écoute défavorables. Cette discussionpeut aller plus loin, aux ajustements desappareils auditifs binauraux – Jeplaiderai que l’ajustement binaural estmeilleur à moins qu’il ne le soit pas. Eton sait qu’il ne l’est pas parce que leporteur de l’appareil auditif sent qu’il n’ya pas d’avantages à porter des appareilsauditifs après l’avoir essayé dans unenvironnement de vie réelle.

L’audiométrie est une mesure tellementgrossière et simpliste mais on comptebeaucoup dessus. Avec l’avènementd’autres tests qui sont supposés évaluerla fonction audiométrique, nous avonsplus de mérite pour faire face à nosclients malentendants. Par exemple, lesmesures de l’émission otoacoustiquesont pathologiques bien avant qu’onpuisse les observer et les seuils du sonpur audiométrique changent. Dans unsens, le temps qu’on observe une perteauditive mesurée par le son pur, biendes dommages à la cochlée se sont déjàproduits. Et avec un dommage continuà la cochlée, nous voyons maintenantplus de changements centraux quidiminuent la capacité decommunication de la personne.

Alors, doit on baser notre décisionclinique de recommander un ou deuxou aucun appareils auditifs sur desseuils audiométriques de pure son –

probablement non, mais plus souventque pas, les régulateurs n’ont pas autrechose sur quoi se baser. C’est bien sûrplus compliqué que ça. Par exemple, estce que l’ajustement de deux appareilsauditifs est un vrai ajustement binauralou y a t il d’autres enjeux de traitementsplus centraux qui limitent l’avantagetotal de la sommation binaurale, laphase d’intégration, et la synthèse ? Il estpar conséquent notre responsabilitécomme profession de mettre à jour nosrégulateurs (qui ont un travail assezdifficile déjà) avec la technologieactuelle, les techniques d’évaluation et laphilosophie clinique. Les lignesdirectrices préférées sont des états desoins minimes. Peut-être, est-il tempsd’avoir “Des lignes directrices depratiques optimales” aussi ?

Dans ce numéro de La revue Canadienned’audiologie, nous avons le plaisir devous présenter un article de ChristopherSchweitzer et Christopher McCarronconcernant des phénomènes assezintéressants avec des auditeursasymétriques qui touchent à certains deces enjeux. Alberto Behar, dans sacolonne Noise about Noise se pose desquestions sur l’utilité des testsaudiométriques, et certains des enjeuxentourant cette question. Et CalvinStaples dans From the Blogs asélectionné plusieurs entrées sur le blogde HearingHealthMatters.org autour desenjeux éthiques.

Peter Stelmacovich, dans sa colonne Thedeafened Audiologist continue sur lethème que plus peut être meilleur. Nousne devrions pas restreindre ce que nouspouvons offrir à nos clients parmi lesmicrophones directionnels, les optionssans fil, et l’utilisation des appareilsd’amplification sonore comme lessystèmes FM– plus peut être mieux. Ilse peut que ce ne soit pas le cas pour

8 CANADIAN HEARING REPORT | REVUE CANADIENNE D’AUDITION

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tout client, mais à moins qu’on leurfournisse l’opportunité d’expérimenterles options que notre domaine peutleur offrir, il n’y a aucun moyen deprédire qui exige quoi.

Gael Hannan continue avec le HappyHoH et nous parle des multitudes dechoses dont une personnemalentendante devrait s’inquiéter. Etdans ce numéro, nous avons unechroniqueuse invitée pour All ThingsCentral – Irene Hoshko se penche surles évaluations des traitements auditifscentraux chez les enfants en 2012 et oùnous en sommes maintenant. DansSpotlight on Science, Lendra Friesen etSamidha Joglekar nous font une mise àjour du traitement oral de la pertesoudaine d’audition neurosensorielleversus les stéroïdes intra tympaniques.De temps en temps, nous avons desclients qui se réveillent avec une perteauditive unilatérale soudaine etinexplicable (ou même un client avecune surdité soudaine) et c’est justement

ces clients qui étirent à la fois notreexpérience clinique et de counseling.C’est un beau survol de la situationcourante et ce que nous devrions direà nos clients.

Ce numéro de la revue canadienned’audition nous fait réfléchir surplusieurs thématiques, bien au chauddevant un feu rugissant, ou au moinsdans un fauteuil pelucheux. J’espèreque vous savourez votre automne, etpour ceux d’entre vous qui avez assistéau dernier congrès de l’académiecanadienne d’audiologie à Ottawa,j’espère que vous avez aussi rencontréde nouveaux collègues et reconnectéavec d’anciens camarades de classes.

Marshall Chasin, AuD, M.Sc., Aud(C),Reg. CASLPOÉditeur en [email protected] Hearing Report 2012;7(5):7-8

Marshall Chasin Receives Award

Congratulations to Canadian HearingReport’s Editor-in-Chief Dr. MarshallChasin who was a recipient of the 2012Queen Elizabeth II Diamond JubileeMedal for his volunteer services withthe National Youth Orchestra ofCanada. The award was presented byHis Excellency the Right HonourableDavid Johnston, Governor General ofCanada.

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froM the [email protected] |

September is here and for many acrossthe country that means the end of

summer and back to school. I teachprofessional ethics for hearing healthcare at Conestoga College so I too amback to school. The course outlines thescope of practice and code of conduct forthe hearing instrument specialist. I amcontinually trying to show the studentscase-based examples with moral andethical implications. I am sure theargument could be made that everydecision we make in our clinicalpractices has a moral or ethicalconsequence, as we work in health care.As audiologists, we pride ourselves inbeing the “best hearing health careproviders” and we are bound to serveour patient population with the highestintegrity. And for the most part I thinkwe meet this criteria. I always express tomy students that the moment the linesbecome grey that should be a sign thatyour decision-making skills have beencompromised. Janet Clarke once told methat we should practice like our picturewill be on the front-page of the paper. Ithink there is some real merit in thatstatement and I decided this blogsummary would focus on ethics. I reallylike these blogs. I hope the readers andyou both feel the same. The first one is areal doozie, thanks for the blog Holly!

By Holly Hosford-Dunn

A few weeks ago, Hearing Economicsventured into Ethical territory – not aplace economists like to visit.Nevertheless, we’re back in thatquagmire of bad decisions, their effectson practices, and whether they are moraltemptations or true ethical dilemmas.The latter surface when there is a clashbetween two or more moral beliefs,referred to as central values. This postsuggests that “Big” carries ethical, if notmoral, weight in health care.

CentraL VaLue: size MattersMayo Clinic agreed last week to pay$1.26 million to the federal governmentfor “knowingly billing Medicare, Medicaid,and other government healthcare programsfor nonexistent pathology work.” MayoClinic has long been the Gold Standardof American health care. It’s a hugeorganization that covers all specialties.Should our Gold Standard be tarnishedjust because it has problems in its billingdepartment? Don’t we all?

Comment: We’ve seen banks and companiesdeemed Too Big to Fail and spared the axe.Now it seems that some health careorganizations are Too Big to be Unethical.I’m just guessing that if I got caught billinggovernment agencies for nonexistentservices and hearing aids, the State ofArizona would yank my license and nevergive it back (they’re like that). Further, theGovernment would hit me up with fines thatwere proportionally huge compared to themeasly $1mil+ bill handed to Mayo. I wouldbe out of business, unable to make a livingprofessionally, and out of funds. By contrast,

it’s business as usual at Mayo except for aone-time dip into petty cash.

Some wit noted that “Corporations arePeople Too… They’re Just BiggerPeople.” You could add to that: “BiggerPeople Can Assume Bigger Risk.” Iqualified my projected demise in theprevious paragraph by saying “if I gotcaught.” Small folks have to think longand hard before doing somethingimmoral like stealing, given theconsequences of getting caught. Not somuch for Big Mayo, where the odds weregood that they wouldn’t get caught andthe penalties for getting caught weresmall and fleeting. Mayo took the riskand they’re probably still ahead,especially since they don’t have toacknowledge blame as part of thepayment. This is not an ethical dilemmafor Mayo. Not only does this fall in therealm of moral temptation, it falls into aspecial Big People category I’m calling“Calculated Moral Temptation.”

Interestingly, it’s the economic view thatis not clear cut in the Mayo case, wherethe economic cost is much larger thanthe accounting cost of the $1.26 millionpenalty. This is where the ethicaldilemma lurks. If I go out of businessbecause I succumb to moral temptation,there is no harm to the community, otherbusinesses, or most people with hearingloss. The case is simple. But, if Mayotakes the wrong moral path and goesunder, the town of Rochester, MN, goeswith it. An entire town loses itseconomic base, professionals lose theirjobs, families are displaced, importantresearch is threatened, severely illpatients’ lives hang in the balance, andcredibility of health care delivery inAmerica suffers. Who wants to be theone who signs off on that order? You’d

By Calvin Staples, MScHearing Instrument Specialistfaculty/Coordinator, Conestoga [email protected]


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have to go into hiding from The GreaterGood who would be out hunting youdown.

Economics and ethics join up in thephilosophy of utilitarianism, espousedby famous 19th century economist andphilosopher John Stuart Mill andencapsulated in his statement:

Actions are right to the degree that they tendto promote the greatest good for the greatestnumber.

Guess Mayo wins this one, based on thegreater good. But their win will probablybring down at least one new governmentregulation on the rest of us. In that vein,it’s worth pointing out that being Bigmeans your actions can be unethical,immoral but NOT illegal. How else toexplain Big Finance company MFGlobal’s apparent success in avoidingfederal fraud charges for its “loss” of overa billion dollars in customers’ monies,on grounds that it was “sloppy” not“criminal.” The “Big” Central Value canbe rephrased as “It’s good to be King.” Toquote a famous 20th century moralphilosopher,

“Steal a little and they throw you in jail.Steal a lot and they make you king.” BobDylan

There is any number of other ethicaldilemmas and moral temptations toconsider in hearing health care,especially if you are an audiologist:protection of intellectual property,stealing patients, steering patients,turning away patients, selling hearingaids without providing implied services,deriding colleagues, handling impair-ments of patients and staff, plagiarism,calculated errors of omission andcommission, billing insurances by all therules … the list just doesn’t stop. But Iam stopping now.

Philosophy and ethics are hard andconfusing because they questiondecisions made at the margins ofbehaviour. This blog is in full retreat,moving back next week to the simpleworld of economics where margins aremeasureable.

http://hearinghealthmatters.org/hearingeconomics/2012/but-that-would-still-be-wrong-moral-and-ethical-decisions-in-hearing-healthcare/

By Holly Hosford-Dunn

Previously, Hearing Economicsdescribed thefts and deceptions inprofessional settings. Transgressionswere bizarre, some absurd, but allactually happened. Most were illegal; allreceived some form of punishment. Thepoint was that owners and managers areresponsible for imposing and enforcingchecks and balances in hearing healthcare environments in order to protectpatients, staff, and assets from theft andmanipulation. Indeed, checks andbalances are important preventivemeasures put in place to protect peoplefrom making bad choices and create areliable, trusting environment.

Which brings us to the topic of today’spost: Illegal or not, do situations exist inwhich stealing or deceptions areethically defensible in hearing healthcare environments? I think I’m onreasonably firm shifting sand when I saythat the Economic view is that all are OKso long as they are not illegal and aredone for the good of the firm. Readersare encouraged to send in stories of legalstealing and deception that helped theircompanies prosper – I’m sure we couldall benefit from such information.

While we anxiously await examples, it’sworth a minute to define terms. Badbehaviour is often described as “morallyand ethically wrong.” But seriously, doesanyone reading or writing this postknow the difference between moral andethical? Can something be morally rightand ethically wrong, or vice-versa? Thisarea has consumed the life of more thanone philosopher, so don’t look for ananswer in this post. However, I wasencouraged to dig a little when Idiscovered that I could ask theUniverse on its brand new Twitteraccount. I haven’t heard back from TheUniverse – making me wonder fleetinglyif I am just a speck – but I quickly leftthat path to seek out more reliable, or atleast closer, experts. Somewhattautologically, it turns out that morals arebeliefs and ethics are “advancedexpressions of morality” based onconsistent reasoning. You have towonder how consistent rationalizationsare handled.

You’re in the moral ballgame if your guttells you that a proposed act is “wrong”(e.g., stealing from the business) or“right” (not stealing). Rushworth M.Killer, deceased ethicist and author ofHow Good People Make Tough Choicescalls these “right-wrong” decisionsmoral temptations: clear-cut decisionsabout behaviours that are widely“understood to be wrong” and provideexcellent career opportunities fortelevangelists. Dealing with what Dr. Killer calls “right-right” decisionsmoves you up to the big leagues ofethical dilemmas, where choices setone central value (not stealing is good)against another (taking money from thewealthy to feed the poor serves theGreater Good) “in ways that will neverbe resolved simply by pretending thatone is wrong.” So much forrationalizing… ethics requires honestyin one’s thinking.

CANADIAN ACADEMY OF AUDIOLOGYPO Box 62117 777 Guelph Line, Burlington ON, L7R 4K2 T: 905-633-7114/1-800-264-5106 F: 905-633-9113 E: [email protected]

BOARD OF DIRECTORS / CONSEIL DE DIRECTION

Victoria LeePresident/PrésidenteAuditory Outreach Provincial Program Burnaby, BC

Steve Aiken President-Elect /Présidente-DésignéeDalhousie University Halifax, NS

Rex BanksPast President/Présidente-SortantCanadian Hearing SocietyToronto, ON

Joy GauvreauDirector/DirecteurCostco Saskatoon, SK

Harpreet GrewalDirector/DirecteurCanadian Hearing SocietyToronto, ON

Bill HodgettsDirector/DirecteurUniversity of AlbertaEdmonton, AB

Isabelle Anne PleauDirector/DirecteurCanadian Hearing Society Toronto, ON

Glynnis TidballDirector/DirecteurSt. Paul’s HospitalVancouver ,BC

Erica WongDirector/DirecteurMount Sinai HospitalToronto, ON

Susan Nelson-OxfordSecretary/SecrétaireVancouver Island Health AuthorityVictoria, BC

Petra SmithTreasurer/TrésorièreHastings Hearing CentresSteinbach, MB

Susan English-ThompsonDirector/DirecteurSackville Hearing CentreSackville, NS

How about those transgressions inhealth care mentioned previously? Werethey moral temptations or ethicaldilemmas? What is the economic view?Below are a few examples, groupedaccording to the aforementioned CentralValues pitted against the good of thefirm.

CentraL VaLue: faMiLyMattersThe poor accountant last weekembezzled $16 million, but her motive–only now revealed – was pure. She usedthat money unselfishly to prop up herson’s failed ambulance business. The bigpicture emerges: A mom helping herson, a family business, ambulancessaving people’s lives, the world a betterplace. Ethically, how can you blame thewoman for repurposing that money tosuch a worthy cause?

A close-knit family business in LongIsland employed 11 family memberswho provided special ed. services todisabled toddlers. In the process, thebusiness is accused of falsifying recordsand overbilling about $2 million. Buthey, the kids got (some) services, the

family prospered, and $2 mil is a dropin the bucket in the program’s $2 billionbudget.

“Your office manager confesses that shestole money from the office account tobuy medicine for her ailing father. Herfather has died, and she offers you acheck from the insurance proceeds topay you back. After you cash the check,do you fire her or forgive her?”

Comment: With notable exceptions (RobinHood, Soprano family) most of us will seethese examples as moral temptations ratherthan ethical dilemmas. It is wrong to steal.

On the other hand, it is not only OK to stealbut stealing is a cornerstone of Robin Hoodand Tony Soprano ethics – one ethic says it’sfor the Greater Good of the Family of Man,the other’s ethic says it’s for the Good of TheFamily. Not stealing (or not doing otherwrong things) would be an ethical dilemmafor those bound by oath to organizationssuch as these.

The economic view is clear cut for thethree cases, unless the Sopranos go intohealth care. Stealing from the firm raises

costs, which reduces supply, raises price,and cuts demand. Not good for thebusiness. Not good for consumers.Separate the transgressors from thebusiness and get the stolen funds back,using legal means if necessary. Beyondthat, any punishments are the purviewof the courts.

In general, professions are not wellserved by instances of moral and/orethical failure. The ripple effects of suchfailures tend to reach consumers, whoreact by complaining. Complaints getthe attention of agencies, which in turnreact by applying scrutiny to theprofession. Life gets really rough whengovernment agencies move fromscrutiny to regulations and investi-gations of the profession and itsmembers. Just ask Tony Soprano, whopractically lives with the Feds in hishouse. He’ll tell you: it’s a lot easier andfar more profitable to police your ownorganization than have the governmentstep in or, worse, take over.

http://hearinghealthmatters.org/hearingeconomics/2012/ethics-of-stealing/Canadian Hearing Report 2012;7(5):9-11.

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| aLL things CentraL


In diagnosing centralauditory processing

dysfunction ([C]APD)the audiologist’s focusshifts from sensory endorgan to the challeng-ing arena of the audi-tory brain. (C)APDclinical practice guide-

lines and position statements are now indevelopment by associations of commu-nication professionals in North America.Educational audiologists recognize theheavy premium placed on the correct in-terpretation of classroom auditory infor-mation before children achieve proficientreading skills. The introduction of elec-tronic multimedia technology to peda-gogy requires children to integrateauditory and visual information fromdisparate sources in real time, accelerat-ing the processing challenge.

ASHA defines (C)APD as “difficulties inthe perceptual processing of auditoryinformation in the CNS and theneurobiologic activity that underlies thatprocessing and gives rise to electro-physiologic auditory potentials.”1 Thetrue prevalence rate of (C)APD thoughuncertain, is estimated at 7%.2 The goalof (C)APD assessment is to provideinsight into, and delineate by deficitprofiling, areas of strength and weaknessin the operation of multiple auditoryprocesses. This objective is realized bysimulating in the test booth, thedisadvantageous reception conditions

children encounter in their everydaylistening environments and by observingwhen and how the processing breakdownoccurs. This knowledge is used to directa remedial effort.

A generation ago, (C)APD in children wasdiagnosed by excluding othercontributory factors. In 2012 thediagnostic process is more rigorous. Yet,as Allen notes, (C)APD test selectionremains difficult as no “gold standard”exists to evaluate the effectiveness of ourdiagnostic tools.3 There are many such“hot topics” in (C)APD assessment andintervention today with only modestconsensus established in their treatmentby researchers and reflective practitioners.At issue are the following and this list isby no means exhaustive:

1. The selection and number of criterion-referenced tests to includein a comprehensive battery.

2. The diagnostic value of using two test procedures to assess a single auditory process when the deficit suspicion index is high.

3. Optimizing test battery diagnostic power and cost effectiveness by balancing sensitivity, specificity andclinical efficiency while avoiding effects of fatigue, attention and motivation.

4. What criteria to use for failure.

5. Facilitating differential diagnosis byincluding materials with limited language load.

6. Managing language confounds in assessing speech-sound disorders inmultilingual children.4

7. Ensuring that selected tests are appropriate for a child’s language development level and maturationaland chronological age.

8. Treating co-morbid conditions in assessment and in interpreting test results, such as, evaluating the impact of disorders of attention, language, learning, global cognition,memory and motivation.

9. Establishing if supramodal tests (e.g., measuring the visual analog ofauditory tests or using instrumentsspecifically designed to evaluate attentional status) contribute to differential diagnosis or if auditory intra/intertest comparisons are sufficient.

10. Determining which formalized conceptual model best diagnoses and categorizes (C)APD deficits andtargets therapies: the Buffalo, Bellis/Ferre or Spoken Language Processing Model.

11. Quantifying the value and reliabilityof an expanding array of

Pediatric (Central) Auditory Processing Assessment In 2012: Where Are We?

By Irene M. Hoshko, M.Sc.(A) Aud(C) OOAQ

electrophysiological potentials to (C)APD pediatric assessment.

12. Customizing a child’s intervention plan and specifying what metric(s) to use in gauging therapeutic response.

13. Investigating the appropriateness and outcome efficacy of computer-assisted therapy programs. Definingwhat constitutes an adequate therapeutic trial. Comparing phonemically-based “bottom-up” interventions; executive-level “top-down” metacognitive/metalinguisticmanagement strategies and concurrent use of both approachesfor sustained therapeutic effect.

14. Examining the importance of fostering self-advocacy in remediation and determining at what age it can be taught.

15. Determining if all (C)APD candidates benefit from evaluation in psychology and speech-languagepathology. Approximately one-thirdof children presenting with learningdisabilities also evidence (C)APD.5

Kelly cautions that the dual-deficit child’s response to educational andtherapeutic programs designed for just one diagnosis may be poor.6

16. Studying the impact on interventionplan design of nonlinearity betweendeficit and functional effect. Children diagnosed with the same deficit profile and magnitude of (C)APD involvement may experience a differential disability impact due to individual differencesin mobilizing personal compensatoryresources; the presence/absence of secondary disabilities and the availability of appropriate familial and academic support.

strategy for (C)aPdassessMentA multidisciplinary perspectivefacilitates (C)APD assessment. Beforediagnostic testing, the audiologistanalyzes assessment results submitted byprofessionals in other areas of expertise.For example, demonstrated problemswith vowels, the consonants f,r, and thand a reported Performance/Verbal IQdifferential are classic potential (C)APDsignatures. However, professionals inother disciplines may arrive at a differentdiagnosis based on test interpretation. Toillustrate: psychologists interpret theWISC-III’s Freedom from DistractibilityIndex as measuring attention andconcentration. In contrast, theaudiologist views the short-term andworking memory demands of this taskas integral to many auditory processes.7

Research supports the audiologist’sview.8

The audiologist carefully reviews resultsand anecdotal comments from screeninginstruments and behavioural inventoriescompleted by instructional personneland parents, such as The Buffalo ModelQuestionnaire9; Children’s AuditoryPerformance Scale (CHAPS)10; ListeningInventory for Education (LIFE)11;Children’s Home Inventory for ListeningDifficulties (CHILD)12; ScreeningInstrument for Targeting EducationalRisk (SIFTER)13; and the Conners’Scales.14 A detailed case historyincluding pertinent medical, develop-mental and academic information isgathered. The verbal and nonverbalparent-child interaction patterns in thewaiting room are observed. Theaudiologist converses informally withthe child; judges their comfort level inthe clinical setting; determines whatmotivates them and establishes rapport.

Peripheral testing evaluates pure tonehearing status complemented with

distortion-product otoacoustic emissions(to evaluate efferent function);immittance; acoustic reflex thresholds(to rule out auditory neuropathyspectrum disorder) and speechdiscrimination in quiet comparingmonaural and binaural performancewith that obtained at competitive signal-to-noise ratios. Numerous signs andbehavioural indicators signalling(C)APD high risk status may emergeduring test. Other observations suggestmedical referral as a hyperacusic childmay benefit from a neurological consult.

The audiologist assesses the sequentialunfolding of diagnostic impressions anduses clinical decision analysis to identifythe best auditory diagnostic strategy for(C)APD testing if candidacy is indicated.Using a hypothetico-deductive strategy,15

a short list of potential (C)APD subtypediagnoses is formed and progressivelyrefined using ongoing clinical testresults. Suspect skills requiringmeasurement are identified and a batteryis built around them, strategicallyselecting from among tests of binauralseparation and integration; temporal,frequency and intensity resolution;auditory discrimination under degradedconditions and temporal sequencing.

referenCes1. American Speech-Language-

Hearing Association. (Central) Auditory Processing Disorders (Technical Report). Retrieved fromhttp://www.asha.org/docs/html/TR2005-00043.html. 2005.

2. Musiek FE, Chermak GD, WeihingJ, Zappulla M, and Nagle S. Diagnostic Accuracy of EstablishedCentral Auditory Processing Test Batteries in Patients with Documented Brain Lesions. J Am Acad Audiol 2011;22:342–58.

3. Allen P. (Central) Auditory Processing Disorders in Children.

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In: Comprehensive Handbook of Pediatric Audiology. Seewald R andTharpe AM. (Eds.), San Diego, Plural Publishing Inc.; 2011.

4. McLeod S and Goldstein BA. (Eds.)Multilingual Aspects of Speech-Sound Disorders in Children. Toronto: Multilingual Matters; 2012.

5. Medwetsky L. Spoken Language Processing: A Convergent Approachto Conceptualizing (Central) Auditory Processing. ASHA Leader2006;11(8):13–17.

6. Kelly DA. Parenting the Child withAuditory Processing Disorders: A Dynamic and Challenging Role. In:Auditory Processing Disorders Assessment, Management and Treatment, Geffner D, and Ross-Swain D, (Eds.) San Diego: Plural Publishing; 2007.

7. Marler JA, Champlin CA, and

Gillam RB. Auditory Memory for Backward Masking Signals in Children with Language Impairment. Psychophysiology 2002;39:767–80.

8. Siekierski BM, Jarratt KP, et al. WISC-III Freedom from Distractibility Index and Measures of Attention in Children. PresentedPaper: 111th APA Conference, Toronto, Canada; 2003.

9. Katz J. The Buffalo Model Questionnaire-Revised. Tampa, FL:Educational Audiology Association;2009.

10. Smoski WJ, Brunt MA, and Tannahill JC. Children’s Auditory Performance Scale. Tampa, FL: Educational Audiology Association;1998.

11. Anderson KL, and Smaldino JJ. Listening Inventories for Education:A classroom measurement tool.

Hear J 1999; 52:74–76.12. Anderson KL and Smaldino JJ.

Children’s Home Inventory for Listening Difficulties (CHILD). Educational Audiology Review 2000;17 (3 Suppl.).

13. Anderson KL, and Matkin N. Screening Instrument for TargetingEducational Risk (SIFTER). Tampa,FL: Educational Audiology Association; 1996.

14. Conners C and Wells K. Conners’ Parents’, Teachers’ and Self- ReportScales. NY: Multi-Health Systems; 2007.

15. Hyde ML, Davidson MJ, and AlbertiP. Auditory Test Strategy. In: Diagnostic Audiology, Jacobson JT,and Northern JL (Eds.). Austin, Texas: Pro-Ed; 1991.

Canadian Hearing Report 2012;7(5):12-14.


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| the haPPy hoh

Over the years asI have morphed

into a “hearing healthadvocate,” I havebeen immersed inpositive hearing com-munication strate-gies. Thanks to mypeers and my hearinghealth providers, I’ve

been dunked, dredged, and baked intoa confident and assertive advocate forpeople with hearing loss.

However, that’s not to say I practice allthese strategies at all times. I certainlyknow what I should be doing, but onoccasion, cracks appear in my polished,hand-crafted suit of communication-and-advocacy armour.

I still have bad hearing moments andfull-on crappy hearing days. It’s at thesevery times that we’re supposed tointone the following mantra: Above all,to live successfully with hearing loss, I willkeep my sense of humour.

But what if you don’t have one? Whatthen is a poor, humourless hard ofhearing person supposed to do? Mysense of humour, although reasonablysound, doesn't always rise to theoccasion, on demand, especially duringa hearing loss moment. While I can tellfunny stories about embarrassinghearing faux pas, I can also guaranteethey weren’t hilarious at the time – atleast not to me, although other peoplemight have had a laugh or two at myverbal non-sequitur. Not only is hearing

loss not particularly funny, growing upwith it can turn you into a worry-wart,or a complete bundle of nerves.

Now that I’m older, I worry about newthings I had never considered. And, I’mnot sure that hearing healthprofessionals are fully aware of thisaspect of their clients, because mosthard of hearing people wouldn’t like totalk about this stuff in public.

“Hearing” people worry when theyactually hear something go bump in thenight. But at least they can figure outhow to react, like grabbing a frying panor whatever to fight off the thing thatgoes bump. We don’t hear bumps in thenight – but we know they must be outthere, because other people say theyare. So, I start to worry – what am I nothearing on a given night? What’shappening out there in the dark – abump, a crash, a yell, a smash? I hearnothing – and trust me, this can keepyou awake, wondering what you’re nothearing. The bags under my eyes arenot hereditary; they grew on my faceout of worry.

What else does a HoH worry about?Oh, just about everything, but here’s apartial list. I worry that

• My shake-awake alarm will stop vibrating before I wake up.

• The battery people will go on strike; my hearing aids and assistivedevices are all battery operated!

• Next year’s flu season will be bad and everyone will wear surgical

masks instead of lipstick. Can youimagine the hell this would cause for speech readers like me?

• My hearing aid will feed back whenI hug somebody – so I hug with myneck stuck out at a weird angle.

• When crossing a busy, noisy street,I won’t hear the sound of a car about to hit me.

• ALL the captioners quit, and we’releft to depend on speech-to-text, voice-recognition software. I knowthat live captioners aren’t perfect, either; in recent TV coverage, the “Archbishop of Canterbury” and “Queen Victoria” were captioned asthe Arch Bitch of Canterbury and Queen Vicious. But with imperfectsoftware, that’s what we would getall the time!

• My husband’s lips will lose their ability to move. Or he’ll get tired ofrepeating himself and will get a new wife who CAN hear through walls.

• My grandchildren will have high squeaky voices. Their moms will say, “Face Nana when you talk to her, sweet pea, she has a hearing loss,” and they will respond, “Tough s--t!”

• My friends will start going out without me, saying, “We didn’t invite you to the new restaurant, darling, because we know how much noise bothers you. But we brought you back some of the paté.” I hate paté.

• My ear hole will close up and I won't be able to wear a hearing aid.

• After I buy my newest $5000

By Gael [email protected]

The Hearing loss Worry-Wart

hearing aids, they’ll go on sale at 50% off.

• That new study linking hearing lossto dementia proves to be true! Apparently, for every 10 decibels ofhearing loss, the risk of dementia increases by 20%. With my 70 dBloss, I reckon I’ve got about 20 minutes before I lose my mind completely.

• I have missed an important, life-changing opportunity because I didn’t hear the phone ring.

• The worst of all – I worry that I willlose my vision. (This one truly keeps me awake.)

These may sound stupid or paranoid toyou and I admit I’m not really thatmuch of a mess, although I do have mymoments. Being cut off from perfectcommunication is stressful. And whenI read that people with hearing loss areprone to depression, anxiety, and socialwithdrawal – it’s enough to make a hardof hearing person crawl under a rock!

So what to do? One option is to dust offthe sense of humour (even though it’snot scheduled to come back on untiltomorrow at 7 am), and get out thereand enjoy! Another option is to tell ouraudiologists about our concerns; theymight be able to help because theyunderstand what we’re going through.Right?Canadian Hearing Report 2012;7(5):16-17.

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| the deafened audioLogist

As an audiologistwith hearing im-

pairment, I routinelywear both the hat of aclinician and the hatof a patient. This al-lows me to see hear-ing loss from bothsides of the soundproof booth. Interest-

ingly the knowledge I have obtainedfrom these two perspectives is differentyet complimentary.

Being an audiologist has taught memuch about how the auditory systemfunctions, how to assess auditoryfunction, and how to properly prescribeand fit hearing aids, cochlear implants,and wireless remote microphones suchas FM systems. As a hearing impairedperson, I have learned firsthand what itis like to live with significant hearingloss. Moreover, I know what it feels liketo struggle to communicate, especiallyin the presence of background noise.

We know as audiologists that the twomain problems of sensorineural hearingloss are

1. Loss of Audibility2. Loss of Clarity

We manage the loss of audibility quitewell as audiologists. If our patientscannot hear well, we provide them withamplification of varying amounts ofgain. Today’s hearing aids intelligentlyprovide different amounts ofamplification as a function of frequency

as well as the original intensity of thesignal. Scene analysis in hearing aidsoptimize gain and frequency responsefor different environments. As thehearing loss increases we provideincreasing amounts of amplification.Should this not restore audibility wenow have non-linear frequencycompression techniques available torestore audibility of high frequencyconsonants. Finally if this is notsufficient, we can refer our patients forcochlear implantation.

We all know that loss of clarity meansthat when there are other noises present,people with hearing impairment willhave a very hard time communicating.Just like amplification, we need toprovide our patients with greater signalto noise ratios as the hearing lossincreases.

The two tools we have at our disposal forimproving the signal to noise ratio aredirectional microphones and wirelessremote microphones, with FM systemsbeing the most common example of thelatter. Directional microphones provideabout a 4 to 5 dB SNR improvement.This amount of improvement issufficient for adults with mild tomoderate degrees of hearing loss. Butonce we get to a moderate-severe degreeof hearing loss (around 60 dB HL), thedirectional microphone won’t beenough. And this is where we start to failto meet the needs of our patients.

So who should get a directionalmicrophone? In my opinion, every

person with a hearing loss, regardless ofdegree of loss would benefit. Yes thereare times when omni-directionalmicrophones are better so we need toprovide options for manual switching oran intelligent hearing aid that knowswhen to appropriately switch based inthe environment. But people withmoderate-severe, severe, and profoundhearing loss must have an FM system ifthey wish to communicate in noise. FMsystems provide about a 15–20 dB SNRimprovement which is what people withsignificant hearing loss will need tocommunicate in noise. Yet whatpercentage of these patients actuallyhave an FM system? It is far too low.Perhaps this is area in which I differ mostfrom my normal hearing colleagues. Iknow firsthand how hard it is tocommunicate in a noisy environmentslike a restaurant, bar, cafe, or car. Icannot imagine functioning without myFM system. As such, I will make sure Ioffer this technology to all patients withmoderate-severe losses or greater.

I recognize the reasons why morepatients do not use remote wirelessmicrophones are varied. But after over20 years’ experience as an audiologistand 48 years experience of living withhearing loss, I remain convinced that thenumber one reason most adults do notuse this technology is because thetechnology was never presented to thepatient I get frustrated with myaudiology colleagues for failing tointroduce this technology. Similarly, I getfrustrated by my fellow people withhearing loss for rejecting technology that

By Peter [email protected]

Hearing loss from Both Sides of the Sound Proof Booth

will be of such benefit to their lives.So here are my pleas:

to audioLogists andhearing instruMentPraCtitioners1. For adult patients, please ensure

that you select a hearing instrumentthat can use an wireless microphone system such as an FMsystem, even if you do not think they need it right away. The FM system can be used with direct audio input, a telecoil, or in some cases a streamer. Make sure the patient knows how to get to the correct program in their hearing device that can use an FM system.Activate the telecoil at least. I knowyou also need to keep things simple, but try not to limitthe patient’s options too.

2. Please introduce the concept of anFM system at least to patients withmoderate-severe losses or greater. At this degree of hearing loss, only

an FM system can provide them with the required signal-to-noise ratio needed to understand speechin a noisy environment.

3. For pediatric patients, please double check to make sure the FM+ M program has been activated. Too often I trouble shoot FM problems in schools, and find this as the cause.

to PeoPLe with hearingLoss1. Please don’t always go with the

smallest possible hearing aid, especially if you have more than a moderate loss of hearing. You likelywon’t be able to use an FM systemand that seriously limits your listening options. But, the hearing aids that can use an FM system arestill quite small! And, FM systems are small now too.

2. Please understand that the hearingaid is but one device that will help

you hear better. You can hear betterin noise if you add another device such as an FM system.

3. Please don’t say the problem is thateveryone else mumbles. It’s not true…you need help. Your audiologistwould be delighted to get you all the help you need.

It is crucial as hearing health careprofessionals we address both theproblems of audibility and theproblems of hearing in noise. If all wedo is restore audibility, we are onlydoing half our job.

Peter Stelmacovich has a regular blogentitled Deafened But Not Silent: How tolive life to the max with hearing loss.http://deafenedbutnotsilent.wordpress.com/Canadian Hearing Report 2012;7(5):18-19.

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sPotLight on sCienCe |

Sudden sensorineural hearing loss(SSNHL) is a common affliction that

promptly poses a threat to the quality oflife of those patients who experience it.SSNHL refers to a unilateral sensorineuralhearing loss of 30 dB or greater over atleast three contiguous audiometricfrequencies with onset and developmentover 72 hours.1–3 SSNHL is a complaintthat is commonly encountered inaudiologic and otolaryngologic clinicalpractice and thus, it is necessary that theclinical audiologist be aware of thepossible etiologies, characteristics, andtreatment options for this condition.

Current epidemiological data related toSSNHL estimates an incidence of between5 and 20 cases per 100,000 people peryear.2 The true incidence may be higherthan these estimates, as individuals whorecover quickly and spontaneously do notoften seek medical attention.2 Whileindividuals of all ages may be affected, thepeak incidence of SSNHL is between thefifth and sixth decade of life with equalincidence in men and women.2,4,5

In their review article entitled SuddenSensorineural Hearing Loss: A Review ofDiagnosis, Treatment, and Prognosis, Kuhnand colleagues provide a thorough

literature review, along with acomprehensive table, of identifiable causesof SSNHL organized into the followingmain categories: (1) autoimmune,(2) infectious that includes Lyme disease,mumps, and toxo-plasmosis, a treatableparasitic infection commonly contracteddue to contact with cat feces or the ingestion of undercooked meat, (3) functional, that includes malingeringand conversion disorder, (4) metabolicthat includes diabetes and hypo-thyroidism, and (5) neoplastic thatincludes vestibular schwannoma andcerebellopontine angle tumour.6 The mostcommon bacterial infections to causeSSNHL in the U.S. are Lyme disease andsyphilis.6 Besides mumps, which is theleading viral cause, other virusesimplicated in the etiology of SSNHLinclude herpes simplex, varicella zoster,entero virus, and influenza.6,7 Vascularpathologies that decrease blood supply tothe cochlea and reduce intra-cochlearoxygen levels are also a possible cause.6

Approximately 5% of patients whoinitially present with SSNHL areultimately diagnosed with some otherotologic disorder as the conditionmanifests over time. In some cases thefinal diagnosis is Menière’s disease, but itmay also be fluctuating hearing loss,

otosclerosis, or progressive SNHL.2,6,7

Despite an overwhelming amount of research in the area, controversyremains with regard to the etiology and appropriate care of patients with this condition, mostly becauserecommendations vary greatly betweenpublications.2,4,7 The prognosis of SSNHLdepends heavily on identifiable etiology,disease process and duration, specificimpact on cochlear structures, andpossible treatment options given theseother factors.6 However, the majority ofpatients with SSNHL have no identifiablecause for their hearing loss and thus thesehearing losses are classified as“idiopathic.”4,6 While many of the knowncauses of SSNHL cause permanenthearing loss due to cochlear and hair celldamage, it has been documented that 45to 65% of patients with idiopathic SSNHLmay regain some pre-loss hearingthresholds without therapy.2,6,8,9 However,prognosis also depends heavily on avariety of risk factors including age atonset of hearing loss, duration ofdeafness, the presence of associatedsymptoms (such as vertigo and/ortinnitus), audiogram characteristics, andthe time between onset of the hearing lossand treatment from a physician.6,7

Oral vs. Intratympanic SteroidTreatment for Sudden

Sensorineural Hearing loss(SSNHl): Important Information

for the Clinical AudiologistBy lendra friesen PhD, and Samidha Joglekar, MClSc (C), Audiologist, Reg. CASlPOCochlear Implant Research Program, Sunnybrook Health Sciences [email protected]

[email protected]


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According to a recent study by Rauch etal., the current standard of treatment foridiopathic SSNHL is a tapering course oforal corticosteroids (either prednisone ormethylprednisone).2 Over the last 15years, intratympanic corticosteroidtreatment by direct injection into themiddle ear has gained wide popularity.2

A theoretical advantage, documented inguinea pig studies, is an increased drugconcentration at the target organ.10

Another potential benefit of intra-tympanic steroid treatment over oralsteroid treatment is reduced systemicsteroid exposure.2 Rauch et al., conducteda multi-centre, randomized trial in orderto investigate the effectiveness of oralprednisone compared to intratympanicmethylprednisone for principal treatmentof idiopathic SSNHL.2 The study tookplace over almost five years and across 16academic community-based otolaryng-ology practices. Participants werefollowed for six months and receiveddoses of either oral prednisone orintratympanic methylprednisone over 14days.2

Overall, their findings showed that theefficacy of both treatments wascomparable. The mean PTA at 2 monthswas 56.0 for the oral-steroid group and57.6 dB for the intratympanic group andrecovery of hearing at 2 months was 2 dBgreater for oral-steroid treatmentcompared to intratympanic treatment.2

The investigators concluded that from thestandpoint of comfort, cost, andconvenience, oral steroids are better thanintratympanic steroid treatment.However, there were no significantdifferences found between either method

in terms of therapeutic impact on SSNHLand hearing loss recovery.2

Although most cases of SSNHL areidiopathic, a number of treatableconditions can underlie SSNHL and thusa medical referral should be madeimmediately in suspect cases so thatefforts can be directed towardsestablishing a medical diagnosis and,most importantly, ruling out anidentifiable underlying cause of thehearing loss.4,6,7 Patients who experienceSSNHL should be cautiously counselledregarding prognosis, as hearing recoverydepends on a multitude of factors.6,7

Standard pure tone audiometry providesthe criteria for diagnosis of SSNHL andalso has prognostic value, as manypatients undergo a series of audiogramsto document recovery, monitor treatment,guide aural rehabilitation, screen forrelapse, and to rule out hearing loss in thecontralateral ear.2 Although many cases ofSSNHL spontaneously improve withouttreatment, the current evidence-basedstandard of care is directed therapyagainst identifiable causes of SSNHL, anda ten day to two-week course of eitheroral or intratympanic corticosteroidtherapy for idiopathic SSNHL.

referenCes1. Merchant SN, Durand ML, Adams

JC. Sudden deafness: is it viral? J OtoRhinoLaryngol Relat Spec 2008;70(1):52–60.

2. Rauch SD, Halpin CF, Antonelli PJ, etal. Oral vs Intratympanic Corticosteroid Therapy for IdiopathicSensorineural Hearing Loss A Randomized Trial. JAMA

2011;305:2071–79.3. Wilson WR, Byl FM, and Laird N.

The efficacy of steroids in the treatment of idiopathic sudden hearing loss. a double-blind clinical study. Acta Oto-Laryngol 1980;106:772–76.

4. Chau JK, Lin JR, Atashband S, et al. Systematic review of the evidence forthe etiology of adult sudden sensorineural hearing loss. Laryngoscope 2010;120:1011–21.

5. Chen CY, Halpin C, Rauch SD. Oralsteroid treatment of sudden sensorineural hearing loss: a ten yearretrospective analysis. Otol Neurotol2003;24(5):728–33

6. Kuhn, M, Heman-Ackah SE., Shaikh,JA, Roehm P. Sudden sensorineural hearing loss: a review of diagnosis, treatment, and prognosis. Trend Amp2011;15 (3):91–105.

7. Byl FM, Jr. Sudden hearing loss: eightyears' experience and suggested prognostic table. Laryngoscope 1984;94(5 pt 1):647–61.

8. Banerjee A, Parnes LS. Intratympaniccorticosteroids for sudden idiopathicsensorineural hearing loss. Otol Neurotol 2005;26(5):878–81.

9. Chandrashekar SS. Intratympanic dexamethasone for sudden sensorineural hearing loss: clinical and laboratory evaluation. Otol Neurotol 2001;22(1):18–23

10. Parnes, LS, Sun AH, Freeman DJ. Corticosteroid pharmacokinetics in the inner ear fluids: an animal studyfollowed by clinical application. Laryngoscope 1999;109(7 pt 2):1–17.


new on the sheLVes |


auditory eLeCtroPhysioLogyA Clinical Guide $99.99www.thieme.comSamuel R. Atcherson, Tina M. StoodyPublication Date: August 2012, 1st Edition392 pp, 130 illustrations | Paperback / softback | ISBN (Americas): 9781604063639

A practical laboratory-to-clinic guide on the basics of auditory electrophysiology Written primarily by audiologists familiar with cutting-edge research in a rapidly changing field,

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provide a more practical organization of the material. In addition to clinical applications and case

studies, this text includes sections on the foundational science and historical background of auditory

evoked potentials as well as clinical practice and management.

the audioLogy CaPstoneResearch, Presentation, and Publication$79.99www.thieme.comMichael Valente, Cathy Sarli, L. Maureen Valente, Amynm M. H. Amlani, Kirsti Oeding, Joshua FinnellPublication Date: June 2011, 1st Edition424 pp, 316 illustrations | Paperback / softback | ISBN (Americas): 9781604063592

The Audiology Capstone: Research, Presentation, and Publication concisely presents the must-know

information for completing every step of your Audiology Capstone Project. From choosing a research

topic and mentor, to conducting the research and publishing the results, the authors provide you with

the essential information for a productive and successful Capstone experience. Structured

chronologically to parallel the Capstones progression, each succinctly organized chapter includes

bulleted lists for fast reference and call-out boxes that provide examples of database tables, as well as

helpful reminders about audiology equipment and software.

handBook of aCoustiC aCCessiBiLityBest Practices for Listening, Learning, and Literacy in the Classroom $39.99www.thieme.comJoseph J. Smaldino, Carol FlexerPublication Date: April 2012, 1st Edition168 pp, 31 illustrations | Paperback / softback | ISBN (Americas): 9781604067651

A practical, reliable reference that helps audiologists and teachers achieve acoustic accessibility in theclassroomWritten and edited by renowned leaders in the field, Handbook of Acoustic Accessibility focuses on the

acoustic conditions, therapies, and technologies that assist audiologists and teachers of hearing-impaired

students in making the speech signal audible, undistorted, and accessible.

Covering topics that range from acoustic measurements in the classroom to American Academy of

Audiology clinical practice guidelines for Hearing Assistance Technology (HAT), this book reflects current

practices and technologies that are designed to maximize the availability of classroom speech signals.


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PediatriC audioLogy CaseBook$64.99www.thieme.comJane R. Madell, Carol Flexer

Publication Date: May 2011, 1st Edition

296 pp, 139 illustrations | Paperback / softback | ISBN (Americas): 9781604063844

Sharpen and enhance your clinical skills in pediatric audiology with this case-based approachPediatric Audiology Casebook bridges the gap between content knowledge and clinical application in an

accessible manner that will enable readers to put learned theory into active practice by engaging them

in problem-based learning. This compendium of key cases is an excellent choice for the classroom,

covering everything from basic and complex diagnostic cases, to hearing aid technology, vestibular

issues, and the management of auditory development. Each case is consistently organized, beginning

with the patient's clinical history and audiologic testing. The authors then pose a series of evaluative

questions to the reader, followed by carefully considered, thought-provoking answers designed to

foster understanding. Cases close with a discussion of the definitive diagnosis, recommended treatment

options, and the final outcome.

VestiBuLar funCtionClinical and Practice Management$79.99www.thieme.comAlan L. DesmondPublication Date: June 2011, 2nd Edition304 pp, 114 illustrations | Hardback | ISBN (Americas): 9781604063615

In an updated and expanded second edition, this essential text continues to provide a dynamic

introduction to dizziness and balance disorders, and a thorough discussion of the tenets of managing

a balance clinic. Vestibular Function: Clinical and Practice Management begins with comprehensive

advice on the function and dysfunction of the vestibular system, and how to perform a vestibular

evaluation. In the following chapters, the author provides insight on the prevention of falls, and the

treatment of vestibular dysfunction. In his expert discussion of the practical aspects involved in

establishing, equipping and operating a balance clinic, Dr. Desmond includes his own unique

perspective on staffing needs and marketing and financial considerations.


When I wasfinishing up

my thesis for my MScin the mid 1990s, Dr. K. K. Charan, oneof the pillars of theSchool of Commun-ication Sciences andDisorders Program atMcGill University,

had at that time recently retired (I metDr. Charan by chance, a few years afterI graduated, in a clinic where I verynervously tested his hearing. Heremarked to me part way during thistest that I should not try to use anymasking that day because even IraHirsch from the CID could not maskhis hearing loss properly.) and he hadleft behind a pile of unwanted books inhis former office. I was a student whowanted to expand his audiologicallibrary inexpensively and so I acceptedthe administrator’s invitation, one hotMontreal summer’s day, to have a lookthrough his books. I was givenpermission to take what I wanted andspent a couple of hours in this darkoffice picking up and putting downmany books from Dr. Charan’s privatelibrary. I ended up with a small pile ofbooks that included an autographedcopy of Experiments on Tone Perceptionby Reinier Plomp from 1966 (includinga very worn free vinyl demo disk), anda first edition of Diana Deutsch’s 1982book The Psychology of Music. Along

with a few books on musical instrumentacoustics, there was also the book thatI am going to write about in this shortreview: The Acoustical Factors AffectingHearing Aid Performance edited byGerald A. Studebaker and IrvingHochberg. If we jump forwards a fewyears to the present (2012), this 32year-old book has ended up being themost likely to disappear from mybookshelf for extended periods of time,and in the next few paragraphs I hopeto explain to you why this is the case.

The Acoustical Factors Affecting HearingAid Performance is a compilation ofpresented papers and discussions froma conference that was held in New YorkCity from June 14–16, 1978. It waspublished in 1980 as part of a series ofbooks entitled Perspectives in Audiologyby University Park Press out ofBaltimore MD, edited by Lyle Lloyd.The list of contributors to this volumereads much like a “who’s who” ofresearchers on acoustics and audiologyworking during the 1970s, some ofwhom are still very active today.Researchers such as Jozef Zwislocki,Robyn Cox, Norman Erber, MeadKillion, Harry Levitt, Margo Skinner,and Edgar Villchur were involved. Thebook covers many topics and so it isdivided into a number of sections. Thefirst section is entitled “AcousticalEffects of the Environment” withchapters on room acoustics and

reverberation to name but two. Thesecond section moves on to presentsome basic acoustics in a sectionentitled “The External Ear, the Earmold,and the Earphone.” The third section isentitled “Modeling Techniques” andintroduces a topic that is very importanttoday in the discussion of real earmeasurement and hearing instrumentfitting software. The fourth section“Frequency Response SelectionTechniques” examines techniques forselecting hearing instruments withregards to gain and frequency response,and includes discussions on masterhearing aids. Tacked on to the end ofthis section is a chapter with somesummaries of the conferencediscussions, where some interestinginsights are made that resonate stillwithin the realm of hearing instrumentresearch. This list of topics is not datedand could have been written yesterday;perhaps this explains why this book isa corner stone within the hearinginstrument literature and one ofMarshall Chasin’s favourite books.

I will now go on to describe some of thechapters in the book within each ofthese sections that I found especiallyinteresting.

aCoustiCaL effeCts of theenVironMent This section contains 5 chapters. Thehighlight of this section, in my opinion,

Acoustical factors Affecting Hearing Aid Performance: A Retrospective Review

Reviewed by Neil S. Hockley, MSc, Aud(C) [email protected]


froM the dusty BooksheLVes |


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is Chapter 2 entitled “Effects of roomacoustics on speech perception throughhearing aids by normal-hearing andhearing-impaired listeners” by AnnaNabelek. (Dr. Nabelek’s recent work hasbeen on the development of theAcceptable Noise Level (ANL) Test thatis a very powerful clinical tool to guidethe fitting and ultimately therehabilitation needed when prescribinghearing aids.) Nabelek begins bydescribing the sounds that we perceiveas a mixture of three components:

1. The original or direct sound;2. The early reflections occurring

shortly after the direct sound; and3. The later more diffuse reflections.

The two groups of reflected sounds (2and 3 above) produce differentperceptual effects. The earlierreflections “colour” the sound; incontrast, the later reflections areresponsible for the prolongation ofsounds, which is more commonlycalled reverberation. Nabelek goes on

to describe the effects on speechintelligibility. For example, if the directsound is quite soft then the earlyreflections will improve intelligibility(with no reverberation). Whilereviewing a number of studies, Nabelekstates that reverberation generallyreduces speech intelligibility but thishas many factors including room size,distance from the source, type andamount of masking, monaural versusbinaural listening, individual factors,and whether or not the listener iswearing hearing aids. In generalthough, wearing binaural hearing aidsin moderately reverberant rooms is notthat different than in anechoicconditions. Reverberation is a complexphenomenon which can makeperceiving speech quite difficult and itis still a challenge for today’s hearinginstruments.

the externaL ear, theearMoLd, and the earPhoneThis, the largest section of the book iscomprised of 6 chapters. The highlightof this section describes some veryimportant work completed in Canada,included in Chapter 6: “The Acousticsof the External Ear,” written by EdgarA.G. Shaw.

Edgar Shaw worked at the NRCresearch laboratories in Ottawabeginning in the early 1950s afteremigrating from the United Kingdom.He did a lot of work which generatedmany patents and publications ontopics such as probe microphones andheadphones. He even served aspresident of the Acoustical Society ofAmerica in the 1970s,1 and devised anumber of experiments to measure theacoustics of the external ear canal usingprobe microphones.2,3 Any probemicrophone measurements made todaycan be traced to Shaw’s pioneeringwork. As clinical audiologists, we take

probe microphone measurements forgranted. Edgar Shaw’s work wasincredibly detailed and required theutmost precision and patience to collectthe data. In Chapter 6, he summarizesthe acoustical transformation of SPL inthe free field to the tympanicmembrane. He began with presentingthe external ear from two points ofview, firstly as an efficient soundcollector especially above 2 kHz, andsecondly as a filter of complex anduncertain characteristics. Shaw statedthat it is hardly surprising that theexternal ear is “an acoustical factoraffecting hearing aid performance” andthat we need to be conscious of itseffects as we fit hearing instruments.Shaw goes on to describe the elementsof the external auditory system startingwith the concha, then the external earcanal, and finally the tympanicmembrane. This brief chaptersummarizes a huge amount of workmostly performed by Shaw himself.The details about the acoustical effectsof the different anatomical parts of theexternal ear are really fascinating, andare something that we as clinicians dealwith every day.

At the end of this chapter, Shaw saysthe following with regards to improvingthe S/N ratio:

…we can imagine a hearing aid inwhich relevant parameters, such asfrequency response and thedirectionality, are adjusted, perhapsfrom moment to moment in anadaptive fashion, to maximize theinformation content of the sound thatreaches the seriously impaired innerear (page 124).

34 years after this was presented at theNew York conference, this goal is stillbeing pursued by hearing instrumentmanufacturers worldwide.

Pictured above: the original book jacket frommy copy of this book.

ModeLing teChniquesThe modeling of the hearinginstruments and the associated acoustictransforms are an important aspect oftoday’s hearing instrument technology.Models of the acoustic performance ofhearing instruments are essential inorder to have software control over thehearing instrument. In this section ofthe book, there are two chapters onmodeling. My favourite of the two isChapter 13 by David P. Egolf and isentitled “Techniques for Modeling theHearing Aid Receiver and AssociatedTubing.” If you look at all the parts of ahearing instrument that can affect thesound, each of these parts can bedescribed mathematically. Mathematicaldescriptions of the microphone,receiver, acoustic coupling methods,etc. can be made and linked together toprovide an accurate picture of thehearing instrument behaviour when itis worn on the ear. Egolf is specificallylooking at the receiver and the tubingeffects, and describes the effectsmathematically. Egolf then goes on todescribe how a computer model can becompared with probe-tube measure-ments within a real ear. One example isthat of tubing length. Basically, thelonger the tubing is, the lower infrequency the first resonance peak. Thetubing length is beyond the control ofthe hearing instrument software butcan potentially be measured with probemicrophone equipment. Mathematicalmodelling techniques play an importantrole in hearing instrument and softwaredesign, in order to obtain an accuratepicture of all of the variables involved inthe path from the free field to thetympanic membrane. Cross calculationswithin these mathematical models are anessential method to verify that thetransformations have been correctlyimplemented.

Clear definitions are needed when

acoustical transformations are employedso that clinicians, researchers, anddevelopers can know that they aretalking about the same thing. Modellingis an incredibly important part ofhearing instrument design.

frequenCy resPonseseLeCtion teChniquesThe final section of this book isconcerned with frequency responseselection techniques. There are fourchapters dedicated to this topic, alongwith a final discussion chapter on avariety of subjects pertaining to the foursections of this book. I did not find thechapters in this section to be as relevantto today’s hearing instruments as theprevious chapters due to the fact thathearing instrument selectiontechniques have changed greatly sincethe time of the New York conference.Clinically, non-linear fitting rationalesdesigned for complex compressionalgorithms such as NAL NL24 and DSLm[i/o]5 in addition to the manyproprietary fitting rationales, areapplied across the hearing instrumentindustry today. However, I found thelast discussion chapter, Chapter 18, tobe very interesting. It consisted of verydetailed minutes of the discussions thatoccurred after the presentations of thetopics (summarized as the chapters inthis book) along with the speaker’sname. The summary of each discussiongave me the impression of being a “flyon the wall” at this historical event.Some of the comments concerningacoustic feedback, for example, are notrelevant today with the use of phasecancellation feedback systems. Someother comments mentioned, such asthose on flexibility of the acousticalcoupling to affect the overallamplification and frequency responseof the hearing instrument, couldhowever have been brought up justyesterday. I have read conference

proceedings in the past, but none ofthem have been as interesting as thediscussions documented in this book.

strengths and weaknessesof this BookThis book has many strengths. Thematerial is both interesting and easy toread. The individual chapters are veryconcise. There are many diagrams andgraphs to make the material more easilyunderstood. This book really has noweaknesses, other than the fact that ithas been out of print for a number ofyears.

why does this Book stiLLdisaPPear froM MyBooksheLf?With any book review there is often astatement about who should buy thisbook. The trouble is that The AcousticalFactors Affecting Hearing AidPerformance is now long out of print,and is probably quite difficult to trackdown. If, however, you ever find one inyour favourite used book store (oronline supplier), I recommend that youbuy it. It would be well worth owninga copy. Perhaps it too will disappearfrequently from your bookshelf likemine. This book is useful for students,researchers, and developers who needto immerse themselves in the acousticsof hearing instrument fittings. It couldbe useful in understanding somefundamental concepts and it could beof historical interest. I find this book tobe a treasure trove of information andit has given me a sense of appreciationfor the complexity of the acousticalknowledge needed to amplify signals toalleviate the negative consequences ofhearing loss. History teaches us a lot,and this book does indeed accomplishthis.

referenCes1. Stinson M and Daigle G. Edgar

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Albert George Shaw 1921-2009. Retrieved from: www.rsc.ca/documents/ShawEdgarElectedin197519212009.pdf. 2009.

2. Shaw EAG. Earcanal Pressure Generated By a Free Sound Field.Journal of the Acoustical Society ofAmerica 1966;39(3):465–70.

3. Shaw EAG. Transformation of Sound Pressure Level from the Free Field to the Eardrum In The Horizontal Plane. Journal of the

Acoustical Society of America 1974;56(6):1848–61.

4. Keidser G, Dillon H, Flax M, Ching T, Brewer S. The NAL-NL2prescription procedure. AudiologyResearch 2011;1:e24.

5. Scollie S, Seewald R, Cornelisse L,et al. The Desired Sensation LevelMultistage Input/Output Algorithm Trends in Amplfication2005;9(4):159–97.


About the AuthorNeil was in the second last class of studentsto graduate from McGill University inAudiology. He often jokes (perhaps toofrequently) that the reason why theprogram was closed in the mid 1990s wasdue to the massive effort required by thefaculty and staff to teach him!

Canadian Academy of AudiologyHeard. Understood.

Académie canadienne d’audiologieEntendus. Compris.

Save the date!

16th Annual CAA Conference and ExhibitionOctober 16 to 19, 2013 in St. John’s Newfoundland

As the editor of the Canadian HearingReport it is my duty to send any new

books that we receive for review out to aperson who is interested in reviewing it.However, I am shirking my duty becauseI want to do the review myself. The firstedition has quickly become a classic andis becoming the most cited text booksfound in reference sections of peerreviewed hearing aid related articles.And this second edition is continuing inthis tradition. There are a few correctionsand additions to this second edition,namely the inclusion of open mold non-occluding fittings — a timely addition.

Each chapter begins with a one-pagesynopsis that clearly summarizes thecontent, and if that is not enough,vertical blue lines are printed in themargin to alert the reader to the moreimportant elements. All references for all

chapters are printed clearly at the backof the book by author. Personally I feelthat this is a more accessible formatwhere the bulk of the research by eachauthor can be easily seen in some formof chronological order. I would also beremiss if I didn’t mention that the font isquite accessible, especially for those ofus who wear bi-focal or progressiveglasses. It is nice to be able to sit back(with a glass of wine) and still see theprint clearly from 18′′ away.

The textbook has 17 chapters, rangingfrom basic concepts to the more esotericand clinical aspects of fitting hearingaids. Each chapter has a nice balance ofclinical, technical, and academic content.

Chapter 1 discusses basic concepts suchas critical bandwidth, but only thoseconcepts that are directly relevant tohearing aids and hearing aid fittings.This chapter finishes with a stroll downmemory lane and takes us from eartrumpets to wireless communicationdevices.

Chapters 2 and 3 review the varioushearing aid components (chapter 2) andhearing aids (chapter 3). There is also anup to date discussion of the variousassistive listening devices that a hearingaid can be coupled with.

Chapter 4 is appropriately titled“Electroacoustic Performance andMeasurement” and indeed touching oneverything relating to this topic. Thischapter ranges from a hearing aidperformance in a hearing aid test boxand 2 cc couple, to the use of probe tubemicrophones in the assessment andverification process. Real ear to couplertransforms are discussed and how thesecan be used when prescribing and fitting

hearing aids. This is continued inChapter 5 with how earmolds, and othercoupling systems may alter the output.There is even a section in Chapter 5 onearmold maintenance such as tubingchanges.

Chapters 6, 7, and 8 review the variousadvanced features of hearing aids suchas the effect of different non-linearcompression schemes, directionalmicrophones, and adaptive technologiesthat seek to minimize microphone noise,acoustic feedback, and a nice discussionof frequency lowering technologies.

The remaining chapters (9–17) bring theclient into the picture and steps awayfrom technology long enough to realizethat we are dealing with people and notears. Chapters on assessing hearing aidcandidacy (chapter 10), and theprescription and the verification of gainand output (chapters 11 and 12), arefollowed by chapters on counselling andoutcomes measures (chapter 13 and 14).

The textbook finishes up with adiscussion of some of the current issueswith binaural hearing aid fittings(chapter 15), a chapter on issues forfitting children (chapter 16), and finallya chapter on the fitting of CROS,BICROS, and implanted hearing aids(chapter 17).

This is a textbook on hearing aids andnot on hearing. It is not intended toreplace other textbooks that deal withthe education and intervention of thosewho are Deaf or deafened. However, ifyou would like to be kept up to date onmany of the hearing aid issues andtechnologies relating to our field, Icannot think of a better text.Canadian Hearing Report 2012;7(5):29.


froM the LiBrary |

hearing aids By harVeydiLLon, 2nd editionThieme Publishers2012ISBN# 9780957816817

REVIEW BY MARSHALL CHASIN, AuD,AUDIOLOGIST

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the noise aBout noise |

Well, well, well!I see eyebrows

lifted in surprise.What a question to beasked! Everyone whohas something to dowith hearing conser-vation will answer is:“Yes, of course!” Isn’tit the first test to be

performed to examine the state of thehearing system? Naturally, there aremany other tests that aim at different as-pects of hearing. There is the audiologictest battery, as well as the otologic testbattery, the vestibular battery, and soon. But, the pillar of any examination isthe modest audiometric test.

So, here, we have the answer to ourquestion, but, also, we may very welldefine the audiometry as a part of ahealth check and as such related to anyother test in the health maintenancefield.

what aBout the testers?Do audiometric technicians have to bequalified? Isn’t it sufficient with readingthe manual provided by themanufacturer, since, in summary ascreening audiometer has only twocontrols: signal’s sound level andfrequency? (Yes, of course, there is alsothe “left” and “right” ear). Even more,when using a computerizedaudiometer, just the “on” button will do

the trick. Does it mean that anyone offthe street can perform industrialaudiometric screening. The answer hereis a resounding no!

There are other things than moving thedials of the audiometer. To start with,there is the everyday’s biological test ofthe audiometer. Then, there is a needfor periodic electroacoustical calibrationas well as a quiet room to carry out thetest. When the person to be testedcomes in, the objectives and procedureshave to be explained. Following are theinstructions on what to do and how torespond to the signals. Finally, once thetest is over, there is the going over theresults and explaining their meaning tothe subject. Not to forget the discussionon the wearing of hearing protectors ifused in the workplace. In some sense,the audiometry is only an excuse tobegin the education of the worker – itis an important excuse, but only thebeginning.

do testers need to Betrained?And what about the testers: do theyhave to be trained? No doubt theyshould be knowledgeable on noise, thehearing mechanism, noise effects on theexposed individuals (auditory and nonauditory), occupational hearing lossand hearing protection and protectors.Finally, they should know about thereasons for, and limitations of air

conduction pure tone audiometry.

do testers need to BeCertified?Now we are getting to a very sensitiveissue: certification: does it has to bedone, who should do it, need for re-certification, etc. Let’s start from the firstquestion: do they have to be certified.Certification, in general, is a way ofconfirming that the person has thenecessary knowledge to perform. Wecan discuss the extension of the word“necessary,” but the bottom line is thatwhen somebody applies for theposition, he should be able to show thathe has the knowledge to perform itproperly. That is, the meaning of thecertification. Details on the trainingprogram, its duration and content canbe discussed, as well as the qualificationof the training institution. The sameapplies to the re-certification. Whatshouldn’t admit discussion is the needfor certification.

what is the situation inontario?Here we are getting to a sore point. TheProvince of Ontario contains probablythe largest workers’ population in anyCanadian province. Here, there arethousands of industrial establishmentswhere hearing tests are performed(using own or retained testers).However, there are no requirements foraudiometric testers, nor there are

Is Audiometric Testing Necessary?By Alberto Behar, PEng, [email protected]


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training facilities nor there are courses(exception should be made with respectto teaching institutions andUniversities, where such a training is apart of graduate and undergraduatecourses.) on that subject. Several yearsago, the Canadian Hearing Society usedto offer a one week – 20 hour coursethat was discontinued. The old OntarioHydro (OH) used to have a trainingcourse as well as a re-certificationcourse for its nurses that wereperforming audiometric tests to the

noise exposed OH workers. That was apart of the hearing conservationprogram that included an audiometricreview team comprised by the chiefmedical officer, the head nurse and amember from the occupational hygieneunit.

isn’t it tiMe to dosoMething?And who should do it? Is thissomething to be done by the Ministryof Labour, the Ministry of Health or

some other institution? At this point,we are trying to raise the question andseek some answers. It’s a veryinteresting issue when you considerthat the ministry responsible for theeffects of occupational noise exposure(Health) has little to do with theprevention of occupational noiseexposure (Labour).Canadian Hearing Report 2012;7(5):31-32.

For over 30 years, thresholdestimation in very young or difficult

to test patients has been accomplishedwith auditory brainstem response (ABR).The ABR is an onset response; a largenumber of neurons must fire at the sametime to elicit the response. To ensure thissynchronous firing, a short durationstimulus is used. The two most commonshort duration stimuli are the click andthe tone-pip.

The traditional click stimulus is a 100 µs electrical pulse that has afrequency range of approximately 100–10,000 Hz. The broad-band nature of theclick provides stimulation of a largeportion of the cochlea, which causes alarge number of neurons to firesimultaneously. The resulting AEP

provides information on the neuralsynchrony of the auditory pathway.

The tone pip (also called tone burst)stimulus assists in the evaluation offrequency specific performance of theauditory system. The frequency-specificstimulus is achieved by presenting a sinewave for a brief duration. The tone pipstimulus is based on the number of cyclespresented. Typically, the rise and falltimes of the stimuli are 2 cycles and theplateau is either 1 or 0 cycles. With thisapproach, the duration of the stimulusvaries with frequency, but the energycontent of stimulus is consistent for eachfrequency.

The ABR response to click and tone pipstimuli is highly efficient and results in a

clear, repeatable waveform; however, theABR is limited by the cochlea’s travellingwave. It takes time for a stimulus to travelfrom the high to low frequency regionsof the cochlea. Lower stimulusfrequencies result in longer response timeor longer latencies. When the traditionalclick stimulus is separated into thedifferent frequency components, theresponse time of the lower frequenciesoccurs later than the higher frequencies.This limits the contribution of the lowerfrequencies to the overall ABR (Figure 1).

soLVing the traVeLLing waVedeLayThe goal of overcoming the travellingwave delay in ABR is not a new concept.In the late 1990s, the stacked ABR wasintroduced as a method of enhancing

researCh and deVeLoPMent foCus |

Auditory Brainstem Response and the Travelling Wave Delay

By laura Prigge, AuD, Sherrie Weller, and lynn Weatherby


About the AuthorsLaura Prigge, AuD, is Application Specialist at GSI; [email protected] Weller is Application Specialist at GSI; [email protected] Weatherby is Senior Product Manager at GSI; www.grason-stadler.com

aBstraCtCE-Chirp is a new broadband stimulus available for the evaluation of auditory brainstem response. Thenew CE-Chirp optimizes the stimulus so that the energy from the stimulus reaches all regions of thecochlea at approximately the same time. This change in the stimulus presentation offsets the mechanicsof the cochlea’s traveling wave and results in an auditory brainstem response waveform that is significantlyincreased in amplitude. The ABR generated by a CE-Chirp has been demonstrated to be as much as twotimes more robust than the corresponding click ABR in normal hearing subjects. CE-Chirp Octave Bandsare additional stimuli that are available for frequency specific threshold estimation. Using the sameprinciple as the CE-Chirp, the CE-Chirp Octave Bands elicit optimal waveforms for frequency specificevaluations.


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Wave V to assist in identifying smallacoustic tumours.1 It was theorized thatthe contribution of the lower frequencyactivity in the cochlea due to thetraveling wave was inhibiting earlyidentification of tumours, especiallywhen the tumours affected the lowerfrequency region of the auditory nerve.Through a series of filtering and masking,

the neural responses to click stimuli wereisolated and “stacked” on top of eachother to generate a picture of the entirecochlea’s contribution to themeasurement of ABR. Benefits of thestacked ABR included early identificationof small acoustic tumours and largerWave V. The stacked ABR, however,requires repeated tracings and post-

acquisition manipulation to the ABRmeasurement adding significant time totesting.

There have been a number of earlystudies to overcome the travelling delayin the cochlea, but the firstcomprehensive description was made byDau et al.2 More recently, a new approach

figure 1. Click stimulus timing and response: Wave V latency is a reflectionof cochlear delay.

figure 2. CE-Chirp Stimulus.

figure 3. Click Stimulus Timing and Response: CE-Chirp.

figure 4. The click and the CE-Chirp have identical amplitude spectra.

to improve ABR recordings has beenintroduced by Claus Elberling andothers.3–5 The CE-Chirp is a new broad-band stimulus designed to enhanceWave V of the ABR through adjustmentof the stimulus frequency composition.This adjustment counteracts thetemporal dispersion of the travellingwave inherent in the cochlea bypresenting lower frequency energy beforehigher frequency energy (Figure 2),resulting in an increased Wave Vamplitude (Figure 3). The CE-Chirpfrequency adjustment maintains thesame frequency content of the click(Figure 4).

The frequency timing, however,maximizes the response of the cochlea,increasing the synchronous neural firingsof the auditory pathway. The increased

neural firings to the CE-Chirp stimulushave been demonstrated to result in ABRamplitudes that are 1.5 to 2 times greaterthan ABR amplitudes to click stimuli innormal hearing subjects (Figure 5).

For frequency-specific thresholdestimation, the tone-pip or tone burst hastraditionally been the most effectivestimulus. CE-Chirp Octave Bands arenow available for frequency specificthreshold estimation. Designed along thesame principle as the broadband CE-Chirp, CE-Chirp Octave Band stimuli(Figure 6) elicit optimal waveforms forfrequency specific evaluation.

CE-Chirp Octave Bands are derived fromthe CE-Chirp stimulus; therefore, thelatencies of the responses will reflect thetiming of the frequencies of the CE-

Chirp. Lower frequency CE-ChirpOctave Band stimuli occur earlier in timethan higher frequencies (Figure 7).

Therefore, the ABR latencies of the lowerfrequency CE-Chirp Octave Band stimuliwill occur earlier than the higherfrequency CE-Chirp Octave Bandstimuli. It is important to note thatresearch indicates that for thresholdestimation, the absolute latency is not ascritical as an identifiable, repeatableresponse.

iMPLeMentation of Ce-ChirPto the aBr eVaLuationCE-Chirp stimuli are ideal stimuli forelectrophysiological threshold estimation.Threshold estimation can be difficult toachieve in a single appointment withchallenging patients such as infants andyoung children. The CE-Chirp and theCE-Chirp Octave Band stimuli have beendemonstrated to generate a repeatableand reliable Wave V response that islarger in amplitude than the Wave Velicited by traditional click and tone-pipstimuli. The robust responses are oftengenerated with fewer averages whichshorten the time of the evaluation.Additionally, the use of CE-Chirp OctaveBand stimuli provides robust and fastfrequency-specific threshold estimationfor a more thorough evaluation.Although clinical studies are not yetavailable for neurophysiologic diagnosticevaluation, threshold estimation is animmediate and effective use for the CE-Chirp stimuli.

CaLiBration and norMatiVedata for Ce-ChirP stiMuLiThe International Organization forStandardization (ISO) has recentlydefined the measurement and calibrationof short duration stimuli relative to theeffect that temporal integration has onhearing thresholds through the ISO 389-6 standard.6 ISO 389-6 provides the

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figure 5. CE-Chirp response follows the expected latency intensity function, but generatesa significantly larger amplitude than the Click response.

figure 6. Amplitudespectra of the CE-ChirpOctave Band stimuli.


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reference threshold hearing values fortraditional click and tone burst signalswhile IEC 60645-3 defines how tocalibrate click stimuli and the tone burststimuli. Provided that the click and theCE-Chirp are stored in the testequipment with same amplitudespectrum the internal calibration settingof the click also will apply to the CE-Chirp. The calibration of the CE-ChirpOctave Band stimuli reference values areprovided by PTB (Physikalish-Technische Bundesanstalt, Brauschweig,Germany).

As is always recommended for AEP

norms, normative data should becollected for the new CE-Chirp stimuliin each clinical environment to ensureappropriate interpretation. Whenutilizing the CE-Chirp and CE-ChirpOctave Band Stimuli, a protocol similarto the following information outlined inTable 1 is recommended.

suMMaryCE-Chirp and CE-Chirp Octave Bandstimuli are exciting new additions to theABR protocol. Available in commercialsystems such as the GSI Audera, thesenew stimuli can help to increase the

clinician’s confidence and reduce testtime for threshold estimation testing.Continued research and publications onthe CE-Chirp are likely to enhance theAuditory Evoked Potential clinicalapplications in the near future.

referenCes

1. Don M, Kwong B, Tanaka C, Brackmann D, Nelson R. The Stacked ABR: A Sensitive and Specific Screening Tool for Detecting Small Acoustic Tumors. Audiol Neurotol 2005;10:274–290(DOI: 10.1159/000086001).

2. Dau T, Wagner O, Mellert V, and Kollmeier B. Auditory Brainstem Responses with Optimized Chirp Signals Compensating Basilar Membrane Dispersion. J Acoust SocAm 2000;107:1530–40.

3. Elberling C, and Don M. Auditory Brainstem Responses to a Chirp Stimulus Designed from Derived-Band Latencies In Normal-HearingSubjects. J Acoust Soc Am 2008;124, 3022–37.

4. Elberling C, Callø J, and Don M. Evaluating Auditory Brainstem Responses to Different Chirp Stimuli at Three Levels of Stimulation. J Acoust Soc Am 2010;128:215–23.

5. Elberling C, and Don M. A Direct Approach for the Design of Chirp Stimuli Used for the Recording of Auditory Brainstem Responses. J. Acoust Soc Am 2010;128:2955–64.

6. International Standards Organization. 389-6. Acoustics - Reference Zero for the Calibration of Audiometric Equipment - Part 6:Reference Threshold of Hearing forTest Signals of Short Duration. Geneva, Switzerland: Author; 2007


figure 7. CE-Chirp Octave BandStimuli derived from the CE-Chirpstimulus.

Table 1. Sample Protocol for CE-Chirp


One of the first activities in the typicalaudiological assessment is to argue

with nature. The right ear gets separatedand isolated acoustically from the left.The test proceeds, the individual earaudiometric results are recorded, andquite possibly, even the best cliniciangives little thought to the underlyingsurprises that may lurk below thethreshold pattern of the then dissectedhearing system. In asymmetrical cochlearpathology the surprises may be especiallynoteworthy. For such asymmetricalclients, with thresholds of one earsignificantly worse (e.g., 35 dB or more)than the other, it may not occur to manyaudiologists to examine the inter-eardifferences at common listening levels.However, despite the fact that mostcommon listening experiences areorganized around “comfortable” listeninglevels for broadband signals (rather thanpure tones at threshold levels), there ismuch that can be learned from simpletests of supra-threshold balancing.Having studied nearly 30 such patients,

we provide a few examples andcommentary.

Simple lateralization tasks wereconducted for 29 asymmetrical subjectsusing a one of two standard clinicalaudiometers (GSI-16 and Fonix FA-10)calibrated with TDH 39P headphones.The subjects were asked to assist, byverbal report, in adjusting the relativepresentation in 5 dB, 2.5 dB, andsometimes 1 dB steps. The characteristicfindings represented by two cases forthose with known or presumed cochlearimpairments are given here.

The first example is for a 49-year-oldfemale with a congenital, severe sensori-neural impairment of the left ear withaudiometric thresholds is shown inFigure 1. Note that the plotting on theaudiometrics is on a logarithmic scale, sothey appear slightly unconventional tostandard audiograms, but all values aredB HL standard notations. No maskedthresholds were detected at 2 kHz and

above. The right ear is essentially normal.The masked air conduction thresholdsfor the Left as shown are obviouslysevere. It is evident that she has athreshold difference for her left/righthearing threshold levels for frequencies250, 500, 750, 1 k, and 1.5 kHz of about60 dB. This subject has worn a hearingaid in the bad ear for over 25 years.Hence, it can be assumed that theimpaired side was accustomed to sensorystimulation, a point of some relevance.History, reflex testing, and otherdifferential diagnostic findings stronglysupport a cochlear site of lesion, ofundetermined congenital cause.

A unique element shown on thisaudiogram (and in Figure 5) is ameasured portrayal of the inter-ear levelsrequired to achieve a “center of the head”perceptual experience at comfortablyloud sensation levels. To obtain thesemeasures a relatively simple protocol wasintroduced1 using standard audiometricheadphones. The listener was asked to

researCh and deVeLoPMent foCus |

Centring Surprises in Asymmetrical listeners

By H. Christopher Schweitzer, PhD and Christopher McCarron, AuD

About the AuthorsChristopher Schweitzer (far left) is senior audiologist and corporatechairman at the Family Hearing Centers of Colorado.Christopher McCarron, AuD, is a rehabilitative audiology specialistat the Family Hearing Centers of Colorado.


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report the location of the perceivedsound using a reference chart shown inFigure 2. Selected signals were manuallyadjusted to each ear independently bythe examiner until the target (center ofhead) was achieved.

With presentation levels to the better earset to a “comfortable” setting, interactive

adjustments were made to the poor earlevel in a bracketing approach until acenter-point position of the interrupted(pulsed) tone signals was reported. Threedeterminations of the levels, withincremental changes as small as 2.5 dB,were done for each stimulus to provideconfidence in the measured levels. Theinitial signals were pulsed tone

frequencies of 250, 500, and 750 Hz forthis subject.It was not difficult for thelistener to reach the desired “center of thehead” level relatively quickly and withoutvariation on the three repeateddeterminations for each signal. Therecorded tonal measures are shown asred/blue bars for this subject in Figure 1.It can be seen that the differences at the

figure 1. Threshold and plotted examples of levels to achieve balancesfor selected signals for one asymmetrical listener with presumedcochlear site of lesion (see text).

figure 2. Illustration of the numbering chart used to locate theperceptual experience for the various signals. listeners were asked havethe experimenter adjust the relative left-right levels until the stimuluswas perceived in a position as near as possible to number 15.

figure 3. Generalized representation of classical “Growth of loudness”patterns suggesting steeper than normal function for sensori-neuralhearing impairment. florentine et al.2–6 have suggested a “softnessimperception” aspect of the abnormality, rather than loudness“recruitment.”

figure 4. Behaviour pattern for ears of a patient with unilateral sensor-neural impairment (Subject described in text and figure 1) showing asimilar nonlinear loudness discontinuity as in figure 3. This figure isillustrative rather than strictly data-based.

two ears converged to substantiallyreduced values of less than 7.5 dB, insome cases less than 5 dB! A steeppattern of “loudness catch-up” isobserved through an assumedcombination of possible unmasked crossover and binaural processing. Thepattern is somewhat similar to the steepgrowth of loudness associated withclassical sensori-neural hearing losspatterns as compared to normal hearingpatterns.

This familiar pattern, and the basis formany amplification assumptions, isshown as a reminder in Figure 3. At anyrate, it should be immediately observedfrom Figure 1 that the inter-ear differencesgreatly constrict at supra-thresholdpresentation levels – levels closer tonormal listening conditions. Moreover,the pattern, when studied at severalpresentation levels, for this listener lookslike that of Figure 4.

An additional method by which speechand music was introduced to collectobservations on non-sinusoidal signalswas introduce on several of the subjects,including for the subject portrayed inFigure 1. The procedure for these

measures follows later in this article.

A second audiometric example is shownin Figure 5. This was a male, age 52, withessentially normal hearing on the left earand severe loss on the right earsubsequent to a vaccine reaction at age50. Some initial spontaneous thresholdrecovery was observed in the impairedear for this subject in the first severalmonths post-onset. The stabilizedthresholds in the severe range are shownin Figure 5 along with inter-ear differencemeasure results. This subject had triedamplification sporadically with limitedsuccess on the impaired right ear.Distortion of external sounds, and of hisown voice, dominated his auditoryexperience, even with very mild gainvalues. Currently, he reports help withlocalization and hearing in quiet withamplification levels far less than standardprescription gain proposals.9 Thebalancing tasks were more difficult forthis subject due to substantial distortionin the otopathologic ear. He was,however, able to achieve repeatableresults shown in Figure 5, including formusic.

Once again in Figure 5 we have plotteddifference levels for selected signal atwhich balance sensations were achieved.The results were again striking examplesof the previously mentioned “catchingup” behaviour for the several frequenciestested. It was clear for this subject, also,that a significantly smaller amount ofdifference for presentation levels to thetwo ears was required to achieve a senseof “center of the head” lateralizationexperience for tones, speech, and musicat comfortable listening levels (CLL) thanimplied by the threshold audiogram. Anexperience of binaural auditoryperception was clearly achieved, bothsurprising and curiously amusing thesubject.

Similar findings were observed for theother participants in these clinicalobservational studies if cochlear site oflesion was presumed. Clearly thepatterns speak to the high value thatNature assigns to the principle of Balance,(with regard to audition, rather than tovestibular function), even when injuryand medical mishaps conspire to disruptit. To re-iterate, differences of 50 and 60dB at threshold were in some casescondensed to 5 dB or less at comfortablesensation levels. It is noteworthy that, inseveral instances subjects reported thatthe auditory “image” jumped rapidlyfrom right to left, requiring a fewmoments to engage the adjustments soas to locate the sound within the head.This usually occurred when a long andsubstantial “ear dominance” made theintroduction of sound to the more severeear particularly unusual.

Another interesting report from severalsubjects with long-term severe deficitswas the experience of a “phantom” imageto the bad side perceived briefly when allstimulation was moved back to the betterside. Audiograms and notes for two suchsubjects are shown in Figure 6, and

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figure 5. Threshold and plotted examples of levels to achieve balances for selected signals for a malesubject with adventitiously acquired hearing loss for the right ear (see text).


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Figure 7 attempts to illustrate theperceptual “cross-over” with an unlikely,but admittedly uncertain, amount ofacoustic cross-over given the presentationconditions. It appears that the higherneurological features of the auditorypathway, cortical activity and synapticpattern tracks associated with theseperceptual tasks makes the task complexand sometimes ambiguous for thelistener. Established neural pathways mayrequire “new registrations” when stimuliare moved and mixed in the mannerdescribed here. Sensitive brain imagingand/or mapping techniques are almostcertainly needed for more comprehensiveanswers.

Generally our observations haveconsistently shown a systematic reductionof the difference to achieve balance as afunction of sensation level. In otherwords, as presentation levels wereincreased to the better ear, the amount ofdifference to the injured ear was furtherreduced as suggested in Figure 5.

It is well-established that large individualdifferences exist in loudness growthpatterns among listeners with sensori-neural hearing loss.4,5 Inter-eardifferences, as in cases of asymmetricalhearing sensitivities, present numerousadditional uncertainties related tobalanced auditory perception. Asmentioned above, some of the measuredfindings for these subjects may be relatedto classical “cross over” stimulation sinceclassical masking was not introduced forthe surpra-threshold measures. However,since the better ear was also receivingsimultaneous stimulation of the samesignal, it is difficult to sort the interactiveaspect. It is also reasonable to speculatethat some post-cochlear processesthrough the brainstem and mid-brainnodal centers may have contributed to thenet experience of de-lateralizedperception. The report of several listeners

A B

figure 7. Illustration of cross-head migration of perception observed in several subjects afterstimulation of the long-term “bad” ear; subsequent stimulation to the better was reported as stilllateralized to the now non-stimulated ear side.

figure 8. Measurement scenario for determining the relative dB spl differences between headphoneswhen subjects adjusted the music from a digital player to a Center of Head position.

figure 6. Two additional samples of assymetrical audiograms on individuals (Males ages, 64 & 53) wehave studied. They have quite different histories and etiologies, and only one has test data at 125 Hz.However, both had confusions of which ear was stimulated in some conditions, including perceivinga signal in the ‘bad” ear when stimulation had returned entirely to the better ear (figure 8). Bothhave worn hearing aids (for different lengths of time) in the worse ear.

of the “phantom image” in the non-stimulated ear seems consistent withsuch a conjecture. Conceivably, suchpost-cochlear pathways may have beenthe dominant effect, but the clinicalresearch reported here did not have themeasurement sensitivity or rigor toinquire deeply into the neuro-physiological mechanisms.

Although most studies of binauralloudness summation7,8 make use ofsymmetrical hearing loss subjects, thisfinding, of an interaction with sensationlevel, is consistent with studies ofbinaural loudness summation patterns asa function of level. It further emphasizesthe uncertain relation between thresholdaudiometry and the typical goal ofamplification – the delivery of normalspeech acoustics to a “comfortably clearlevel” (CCL), especially when inter-eardifferences are present.

non-CLiniCaL soundsFor many of the subjects we extendedthese studies to the related question ofwhether binaural perception of signals

for unilateral or asymmetrical sensori-neural impairments can still produce‘center of the head’ lateralization, orstereophonic listening experiences – atpreferred listening levels? In otherwords, do acoustically dichotic signals(not diotic) of stereo music presented viaheadphones converge to an enjoyableauditory experience if and when thelevels at the two ears can beindependently adjusted for ears ofdissimilar audiometric sensitivity(threshold)? This was addressed by useof a proprietary In Balance control madeby Able Planet, Inc. The listener/subjectwas able to adjust the Left/Right levels ofsignals delivered from an MP3 playerinto a set of consumer audioheadphones. The In Balance control useslinear tapering to adjust inter-eardifferences by up to 24 dB. The musicand some recorded speech data shown inFigures 1 and 5 were obtained by havingthe subjects listen to a musical passageplayed into a set of Able Planet NC-200headphones and adjust the In Balancecontrol. The subjects first adjusted thebasic volume for a passage of BonnieRait’s “Something to Talk About” playedat a comfortably clear level (CCL). The15 subjects in this part of the studyindicated the passage (and level) wasenjoyable. They adjusted the balancecontrol to reposition the sound until amiddle of the head position wasachieved. This was usuallyaccomplished in a few seconds after over-adjusting briefly to the worse ear, beforeconverging on the best position. Thecontrol was then ‘locked’ into positionwith the secure toggle switch.

By splitting the signal to a matched set ofheadphone’s the sound pressure leveldifference between the individual earoutputs were obtained on a standardsound level meter in A-weighted slowmode secured into a coupler. When the

subject reported a position at (or near)the target of Number 15 (Figure 2)position on the head chart, the balancecontrol was locked and a pink noisesignal was played through the MP3device. Measured pink noise outputdifferences in dB SPL (sound pressurelevel) for the two earphones wererecorded as inter-ear level differences (seeFigure 8). For the first subject describedabove those differences ranged from 2.5dB to 7.5 dB, depending on the level atthe better ear as shown in the Figure 1details. Figure 9 adds further descriptivedetail of the adjustment protocol.

suMMaryAsymmetrical hearing loss patterns withdifferences of 35 dB or greater areunderstood to present diagnosticchallenges of masking in order to isolatethe more severe ear. They also introduceconsiderable uncertainty as to inter-eardifferences at supra-threshold levels. Incochlear-based asymmetries there is thestrong likelihood that differences betweenear responses at threshold, especially inthe case where one ear is essentiallynormal, will show considerable ‘catchingup’ at supra-lateralization of bilaterallypresented sound stimuli such as in theuse of headphones for entertainment.Typical listening levels for such purposesare, of course, considerably moreintensive than barely audible (threshold)levels. We have described some clinicalresearch that attempts to joinaudiometrics with commonplacelistening experience. The availability ofa reliable balance control may notablyimprove the stereo listening enjoymentof unilaterally impaired, or asymmetricallisteners without much required offset.

Not surprisingly individual differencesfor the subjects we have observed in thisaudiometric category were noteworthy.The issues that confound unilateral and


figure9. Illustration of the use of the In Balancecontrol to achieve a “Center of Head” experiencefor the music passage. Differences were measuredusing a steady pink noise as shown in figure 3. forthe subjects described in figure 2 and severalothers, depending on the loudness listening level,the differences ranged from 2.5 to 7.5 dB. Notsurprisingly the least differences occurred atlouder sensation levels in patterns such as shownin figure 4.


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asymmetrical sensori-neural hearing losswere operating to make each subjectunique in his or her auditory history andinter-ear dissimilarities. Nevertheless,the robust and fundamental binauralprocessing of signals, even from ears ofunequal sensitivities and stimulationhistories could be readily observed for allthree subjects.

The clinical tradition for hearingassessment is to first separate the twonaturally communicating acousticalsensors (ears), and then to measure themindependently. Perhaps it ischaracteristic of the discovery processthat sometimes a great deal can belearned about complex systems, such ashearing, from modest changes inprotocol and the serendipitouspresentation of a few individuals withnon-standard hearing patterns. Thesefindings are instructive at several levelsof discourse.

These carefully obtained, but admittedlynot rigorously researched, observationsof a relatively small group of listenerswith asymmetrical hearing patternssuggest numerous ‘surprises’ await theinquisitive and engaged clinician. It isnoteworthy that many subjects indicatedthat being able to re-position thelistening experience towards a center ofthe head position was a desirable feature.In several instances it produced anunprecedented and enjoyable auditorysensation.

The corresponding audiologic findingson these listeners’ binaural balancingexperience under controlled conditionsare of interest of themselves. The presentfindings, while obviously varied amongthe members of the small sample size, are

patterns uniquely pertaining to sensori-neural type of impairment, presumablyreflecting cochlear damage of varyingdurations. This assumption wassupported by tests on two additionalasymmetrical subjects with entirelyconductive sites of lesion. Theirexperience was completely different. Inboth cases it appeared that balancedperformance might possibly only occurif the large threshold differences wereessentially maintained and carried up tothe supra-threshold listening levels. Thiswas both impractical and outside theinterest of the present investigation.

While the various differences betweenthe subjects argues against averagingthese findings it was tempting to simplycompare the Average Thresholddifference between 'good' and 'bad' earswith the Average Balanced leveldifference. Those numbers are: 49.2 dBThreshold versus 7.4 dB forsupratheshold Balance values across allthe various signal types and sensationlevels. Clearly, something similar to thespeculative pattern of Figure 4 was atwork. Clinicians are encouraged toconsider the potential for significantdifferences that may occur ‘between theears’ at supra-threshold listening levels inthese types of patients.

aCknowLedgeMentsVariations of Figures 1–5, and 8 and 9appeared in the Schweitzer and Smitharticle in Hearing Review (16:4). Theauthors are grateful to the publishers ofHR for permission for their use in thispublication.

Some data collection support wasgratefully received from Able Planet, Inc. referenCes

1. Schweitzer C and Smith D. Meetingin the Middle with Unequal Ears. Hear Rev 2010;16(4):19–26.

2. Florentine M. Softness Imperception:Defining a Puzzling Problem. Hearing Health 2004;20(1):31–34.

3. Florentine M. Page 10: It’s Not Recruitment – Gasp! It’s Softness Imperception. Hear J 2003;56(3):10–15.

4. Marozeau J and Florentine M. Loudness Growth in Individual Listeners With Hearing Losses: A Review. J Acous Soc Am 2007; Express Letters DOI 10.1121:August.

5. Buus S and Florentine M. Growth ofLoudness in Listeners with CochlearHearing Losses: Recruitment Reconsidered. J Assoc Res Otolaryng2001;5:120–39.

6. Buus S, Mus̈ch H, and Florentine M.On Loudness at Threshold. J AcoustSoc Am 1998;104:399–410.

7. Epstein M and Florentine M. Binaural Loudness Summation for Speech and Tones Presented via Earphones and Loudspeakers. Ear and Hearing 2009;30(2):234–37.

8. Hawkins D, Prosek R, Walden B, andMontgomery A. Binaural Loudness Summation in the Hearing Impaired.J Speech Hear Res 1987;30:37–43.

9. Schweitzer C and Wakefield E. Gentle Amplification Treatment for Severe Unilateral Cochlear Injury. Paper Presented at ASHA Convention. New Orleans; 2009.


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