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Module 2: Main Areas of Phonetics

Contents:

2.1 Introduction

2.2 Main Areas of Phonetics: Articulatory, Acoustic and Auditory;

2.3Phonetic Transcription: The International Phonetic Alphabet; Two main types of phonetic transcription

Objectives

• To introduce students to the three main areas of phonetics and to the phonetic script that is used in transcribing speech into symbols that can be interpreted unambiguously by linguists and other professionals interested in speech.

2.1. Introduction In the last module, we tried to get a general idea about the important aspects of the

study of speech sounds. In the present module and the modules that follow, we look

Subject name: Linguistics

Paper number & Title:

02; Introduction to Phonetics & Phonology

Paper Coordinator Pramod Pandey Centre for Linguistics, SLL&CS, Jawaharlal Nehru University, New Delhi-110067

Module id Lings_P2_M2

Module title Main Areas of Phonetics

Content Writer

Pramod Pandey

Email id pkspandey@yahoo.com

Phone 011-26741258, -9810979446

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at specific topics. In the present module, we introduce ourselves to the main areas of

Phonetics, and to the International Phonetic Alphabet.

2.2 Main Areas of Phonetics: Articulatory, Acoustic and Auditory As discussed in the previous module, Phonetics is the study of the physical

properties of speech sounds in three aspects- production, transmission and

reception. Accordingly, there are three branches of Phonetics, namely, Articulatory

Phonetics, Acoustic Phonetics and Auditory Phonetics. All the three branches

together give us crucial information about speech sounds. We can understand the

basic concerns of each of these branches with the help of examples.

2.2.1 Articulatory Phonetics

Let us begin with articulatory phonetics first. Given the sounds p, t, n, e and i as in

the words pit, pan, pen, and pin, they can be differentiated in terms of their

articulation involving different organs of speech. The organs of speech are

presented in Figure 2-1 below:

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Figure 2-1: Organs of Speech http://2.bp.blogspot.com/_KX5Z_XzSA8A/SmEiX57nYkI/AAAAAAAAAAY/qhUZxfauFN4/s400/chp_vocal_tract.jpg

The study of which articulators are involved in the production of speech and how

they are used enables us to use labels to identify them. Speech sounds may need to

be described in groups or individually. Thus when we have to refer to the

consonants [p b t d k ɡ] in English, we use the term Plosives. For the subset of

consonants [p t k] from the larger group of plosives in English, we use the label

‘voiceless plosives’. Similarly we use the label ‘mid vowels’ for [i i: u u:]. These labels

are based on the broad characteristics of articulation, such as ‘plosive’, ‘nasal’,

‘voiceless’, ‘voiced’, ‘fricative’, ‘vowel’, etc. Notice that the description of the sub-

groups of larger groups involves more terms, as, for example, ‘voiceless plosives’ for

[p t k], and only ‘plosives’ for [p b t d k ɡ] for the plosives in English.

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Languages differ in terms of the number of speech sounds found in them in specific

groups. Thus, Indo- Aryan languages, such as Magahi and Marathi, have a much

larger set for plosives: [p b pʰ bʱ, t d tʰ dʱ, ʈ ɖ ʈʰ ɖʱ, k ɡ k ʰ ɡʱ]. Here we will need

more terms for describing the sub-groups of sounds. Try to find out the descriptive

terms you need to describe the following subgroups among the plosives listed

above:

2/1 a. [b d ɖ ɡ]

b. [pʰ tʰ ʈʰ kʰ]

c. [bʱ dʱ ɖʱ ɡʱ]

d. [b bʱ d dʱ ɖ ɖʱ ɡ ɡʱ]

As hint, use the following terms for labeling the groups: plosives, voiced, voiceless,

aspirated, and unaspirated. For the answer, go to the end of the module.

Care has to be taken to ensure that the labels describe large and small groups

of sounds as well as specific sounds. As linguistics is a scientific study of language, it

has to be ensured that the labels, terms and symbols that are used in any of the

levels of linguistic analysis are unambiguous, that is there is one to one

correspondence between them and their significance or value. Thus no two distinct

sounds can have identical labels. Thus, continuing with our discussion of plosives in

English, we must distinguish between [p], [t], and[k] further. We find that although

all the four are plosives and voiceless, they are pronounced at different places in the

mouth:[p] is pronounced by the lips, so it is termed ‘bilabial’, [t] is pronounced by

the tip and the blade of the tongue against the point behind the upper teeth called

the ‘alveolar ridge’, so it is termed ‘alveolar’, and [k] is pronounced by the part of the

tongue called ‘back’ against the velum and so it is termed ‘velar’ . When we consider

other sounds of English, e.g. [m] as a nasal, and [u] as a high vowel, then we have to

give precise labels to distinguish them: ‘voiced bilabial nasal’ for [m] and ‘voiced

alveolar nasal’ for [n], ‘short, high, front vowel’ for[i]and ‘long, high, back vowel’ for

[u:]. In general, a three-term label is adequate to identify a speech sound

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individually. However, in certain cases a four-term label may be necessary for

identifying both consonants and vowels. For example, in a language that has the

sounds [p], [pʰ], and [b], there is need to have a four-term label- ‘unaspirated,

voiceless, bilabial, plosive’ for [p] , ‘aspirated, voiceless bilabial plosive’ for [pʰ], and

‘unaspirated, voiced bilabial plosive’ for [b]. In a language in which we have the

sounds [p], [pʰ], and [b], and another modified sound, such as [pʲ], as in Kashmiri,

we need a five-term label- ‘palatalized, unaspirated, voiceless, bilabial plosive’. No

more than five-term labels are required to identify speech sounds. The labels are

dependent on some aspect of the production or articulation of the speech sounds, as

well as the presence of the number of sounds in a group. Thus, if language has only

voiceless plosives, the terms ‘voiced’ and ‘voiceless’ are not required for labeling

plosives, as all of them are voiceless. A more detailed discussion of the different

processes of articulation is presented in Module 3. Take a look at the live video

of the movements of articulators during the production of speech.

LIVEVI~2.MP4

Live video of movements during speech production (MRI at 20 ms.)

https://www.youtube.com/watch?v=uTOhDqhCKQs&noredirect=1

2.2.2 Acoustic Phonetics

Just as speech sounds have articulatory characteristics involving the various organs

of speech that distinguish one sound from another, they also have acoustic

characteristics which differentiate one sound from another. These characteristics

have to do mainly with small variations in air pressure that can be sensed by the ear

and studied by instruments such as the sound spectrograph and oscillograph. The

variations in the air pressure that are of greatest importance are fundamental

frequency, amplitude and formants. These terms are understood thus.

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The fundamental frequency of speech sounds is the rate of the repetition of the

cycles of air pressure. It varies with each individual, and can also characterize broad

groups like male and female speakers, and, further, children and adults among

males and females. Typically, males have the fundamental frequency of 85-155

cycles per second called Hz, the basic unit of frequency measurements. The range is

higher for females, typically 165-255 Hz. Infants have even higher frequency range,

400-600 Hz. In musical renderings of the various ‘ragas’ in Indian Classical music, it

is the variations in the fundamental frequency that the singers try to render. A

speaker renders them according to their own range of fundamental frequency.

Apart from the rate of the repetition of the cycles of air pressure, the relative

increase in air pressure distinguishes speech sounds. The increase in air pressure is

seen as the distance the air particles travel from the place of rest. The increase in air

pressure gives the amplitude of a speech sound, and is measured in decibels (dB).

The following diagrams illustrate the notions of fundamental frequency and

amplitude.

Figure 2-3: Pitch and Frequency

http://www.physicsclassroom.com/class/sound/Lesson-2/Pitch-and-Frequency

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Thus, the air pressure is higher in a sound like [a:] in the first vowel in father, than in

[ə] in the second vowel.

One of the features of speech sounds is that apart from the fundamental frequency

(F0) there are also overtones of the F0. About three or four overtones of F0 in general

distinguish speech sounds, and typically vowels sounds. The reason for the

overtones to be critically involved in the transmission of vowels is that they are

produced by periodic wave forms, that is, regular fluctuations in air pressure. In a

vowel sound, the air in the vocal tract vibrates at three or four frequencies

simultaneously. These overtones are the resonant frequencies of the vocal tract

shape in producing a vowel. That is how every vowel is heard as distinct from

another vowel. If the vocal tract changes for a different vowel, the resonant

frequencies also change. These resonant frequencies are called formants. The three

main formants, F1, F2 and F3 relate to (a) the openness of the vocal tract, (b) the

front-back differences in the vocal tract and (c) the position of the lips. These are

diagnostic features of sounds that are voiced, and especially of vowels. All these

properties of wave forms are analyzed by sound spectrographs and oscillographs.

(Notice the use of the terms spectrograph and spectrogram. The machine here is the

spectrograph, while the picture that it produces is the spectrogram.) These devices

give visual records of speech sounds. The oscillograms and spectrograms of a clause

in Hindi are produced below for illustration. The sentence is, as in 2/2

2/2 /a:dmi: e:k ʈe:bul kʰı̃:ʧ rəha: hæ:/ Man one table pull CONT BE-3PS-PRES

‘The main is pulling a table’ The picture, produced in 2-4, has three parts- the oscillogram on top, the

spectrogram in the middle, and the duration at the bottom.

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Figure 2-4: Scillogram and spectrogram of the Hindi sentence, ādmī ek Table khiNc rahā hai, ‘The main is pulling a table’.

Notice that in the above picture the frequency components of the segmental speech

sounds are shown in the middle portion and the amplitude is shown in the top

portion by the darkness of the waves. The vowels and the consonants are

distinguished by the continuation of the frequencies and breaks respectively. While

all vowels have all the four frequencies included in the graph, consonants may have

none or only one or two. Each segment has its own pattern. We learn to detect them

as we spend time looking at them.

Duration is also an important parameter in speech. The duration of the entire

utterance (1.285 seconds) is given at the bottom in Figure 2-4. It is possible to

extract the duration of each portion of the utterance, including the segment. Simple

examples of the durational difference between sounds are long and short vowels,

e.g. [i] and [i:] as in sit and seat, or single and double consonants, as in the Hindi

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words [pəta:] ‘address’ and [pətta:] ‘leaf’. Durational measurements are especially

important in the study of prosodic phenomena such as stress, tone and intonation.

Look at the vowels in the word banana, in which the middle ‘a’ is stressed, while the

beginning and the ending ‘a’ are not stressed: ba.ˈna.na. When you pronounce the

word, you will find that you tend to produce the stressed ‘a’ with greater length than

the unstressed ‘a’s.

In the last seventy years, there has been a lot of advancement in our knowledge of

the phonetic properties of speech sounds. The advancement has mainly depended

on the invention of new and sophisticated tools. The field of acoustic analysis of

speech sounds today makes crucial use of equipment, such as the spectrogram, the

oscillogram, as was mentioned above. It is however the availability of digital

computers for phonetic research in general that has made the study of the acoustic

properties of speech easily accessible. Recorded speech is now very close to natural

speech. It is common practice today to carry out acoustic analysis of speech based

on digital recordings in laboratories and apply software for their acoustic analysis.

There are tools such as EMU and Audacity that are helpful in digital recording and

sound editing. There are also tools such as PRAAT, Speech Analyzer and Wave

Surfer that are used widely for acoustic analyses.

Figure 2-5: Students working in the lab

2.2.3 Auditory Phonetics

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Auditory phonetics is concerned with the study of the way sounds are perceived, or

in other words, heard and interpreted by the hearer. While articulatory processes

are easily accessible for observation, auditory processes of speech perception are

much less amenable to direct observation, and we do not have enough knowledge of

how the entire process of the perception of speech sounds takes place. Auditory

processes are heavily dependent on human physiology, the complex structure of the

human ear, and its relation to the brain and the psychological process of

interpreting the information received by the brain through the ears.

The Speech Chain.flv http://www.youtube.com/watch?v=puYbFENTBYI

(See in Learn More)

The field of auditory phonetics, as compared to that of articulatory phonetics and

acoustic phonetics, is still vague and developing. However, it is not difficult to see

the importance of the field of auditory phonetics to linguistics, especially when we

consider facts such as the following:

• A speaker can produce a speech sound, say [i], with different articulatory gestures, yet the listener hears and identifies them as one.

• The speech sounds produced are mixed with irrelevant background, but the listener filters them out.

• Speakers have their idiosyncratic features of speech, that may result in one sound being produced as another, e.g. [ɛ] being produced as [e], yet the listener does not confuse them as two linguistic sounds.

• The sound waves that travel to the ear of the listener contain information that is often superimposed on one another and non-discrete, yet the listener perceives them as discrete speech sounds.

Auditory phonetics essentially involves two processes- one interpreting the acoustic

information by the ear and the brain, and the other interpreting the phonological,

semantic and pragmatic information. Often only the acoustic information is not

enough to interpret the meaning of the speech signal; the listener has to interpret it

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according to the phonological structure of the language. The two phenomena must

be studied both independently as well as complementarily. This is different from the

situation in acoustic phonetics, where all the information has to be studied as a

single phenomenon. It is because of the complexity and haziness of the field of

auditory phonetics that our focus in this course is on articulatory and acoustic

phonetics.

It is interesting to note that there is a redundancy in terminology that has come to

be in phonetics on account of the use of different terms for roughly the same

phenomenon. Thus the acoustic terms Fundamental frequency and Amplitude have

their rough equivalents as Pitch and Intensity or Loudness, respectively. The terms

long/ short, voiced/ voiceless, aspirated/ unaspirated are auditory terms that are

used for studying the articulation of speech sounds. The main focus in the phonetic

study of speech sounds is on acoustic phonetics. In acoustic phonetics, we try to find

out the main acoustic cues to the auditory and articulatory distinctions that

speakers and listeners make. What these cues are is the subject matter of discussion

in later modules.

Summary

We discussed above the three main areas of phonetics and tried to see how they vary in their approaches. We tried to explain to you our focus on articulatory and acoustic phonetics in the present course, even though the study of the auditory aspects of speech is of much significance.