Chapter 1

Articulation and Acoustics

Phonetics is concerned with describing speech. There are many different reasons

for wanting to do this, which means that there are many kinds of phoneticians.

Some are interested in the different sounds that occur in languages. Some are

more concerned with pathological speech. Others are trying to help people speak

a particular form of English.

SPEECH PRODUCTION

Making speech gestures audible involves pushing air out of the lungs while producing a noise in the throat or mouth. These basic noises are changed by the actions of the tongue and lips.

You will find that you can do it, but it is much harder than talking when breathing out. When you talk, air from the lungs goes up the windpipe (the trachea, to use the more technical term) and into the larynx, at which point it must pass between two small muscular folds called the vocal folds. If the vocal folds are apart (as yours probably are right now while you are breathing in and out), the air from the lungs will have a relatively free passage into the pharynx and the mouth. But if the vocal folds are adjusted so that there is only a narrow passage between them, the airstream from the lungs will set them vibrating. Sounds produced when the vocal folds are vibrating are said to be voiced, as opposed to those in which the vocal folds are apart, which are said to be voiceless. The difference between voiced and voiceless sounds is often important in distinguishing sounds. In each of the pairs of words fat, vat; thigh, thy; Sue, zoo, the first consonant in the first word of each pair is voiceless; in the second word, it is voiced. The air passages above the larynx are known as the vocal tract. The phonation process is the name given to the actions of the vocal folds. Only two possibilities have been mentioned: voiced sounds in which the vocal folds are vibrating and voiceless sounds in which they are apart. The possibility of the airstream going out through the mouth, as in [ v ] or [ z ], or the nose, as in [ m ] and [ n ], is determined by the oro-nasal process. The movements of the tongue and lips interacting with the roof of the mouth and the pharynx are part of the articulatory process.

Speech Production

SOUND WAVES

Linguists and speech pathologists need to understand how certain sounds become confused with one another. Speech sounds, like other sounds, can differ from one another in three ways.

They can be the same or different in (1) pitch, (2) loudness, and (3) quality.Two vowel sounds may have exactly the same pitch in the sense that they are said on the same note on the musical scale, and they may have the same loudness, yet still may differ in that one might be the vowel in bad and the other the vowel in bud. On the other hand, they might have the same vowel quality but differ in thatone was said on a higher pitch or that one of them was spoken more loudly.

Sound consists of small variations in air pressure that occur very rapidly one after another.

The ordinate (the vertical axis) represents air pressure (relative to the normal surrounding air pressure), and the abscissa (the horizontal axis) represents time (relative to an arbitrary starting point). The smaller variations in air pressure that occur within each period of one-hundredth of a second are due to the way air vibrates when the vocal tract has the particular shape required for this vowel.

PLACES OF ARTICULATORY GESTURES

The parts of the vocal tract that can be used to form sounds are called articulators. The articulators that form the lower surface of the vocal tract are highly mobile. Try saying the word capital and note the major movements of your tongue and lips. The lips come together in the formation of p and then come apart again in the vowel. The tongue tip comes up for the t and again, for most people, for the final l.

This is called the alveolar ridge. Most people cannot curl the tongue up far enough to touch the soft palate, or velum, at the back of the mouth. The soft palate is a muscular flap that can be raised to press against the back wall of the pharynx and shut off the nasal tract, preventing air from going out through the nose. In this case, there is said to be a velic closure. The remainder of the body of the tongue may be divided into the center, which is partly beneath the hard palate and partly beneath the soft palate; the back, which is beneath the soft palate; and the root, which is opposite the back wall of the pharynx. Bearing all these terms in mind, say the word peculiar and try to give a rough description of the gestures made by the vocal organs during the consonant sounds. You should find that the lips come together for the first sound.

The principal terms for the particular types of obstruction required in the description of English are as follows.

1. Bilabial

(Made with the two lips.) Say words such as pie, buy, my and note how the lips come together for the first sound in each of these words. Find a comparable set of words with bilabial sounds at the end.

2. Labiodental

(Lower lip and upper front teeth.) Most people, when saying words such as fie and vie, raise the lower lip until it nearly touches the upper front teeth.

3. Dental

(Tongue tip or blade and upper front teeth.) Say the words thigh, thy. Some people (most speakers of American English as spoken in the Midwest and on the West Coast) have the tip of the tongue protruding between the upper and lower front teeth; others (most speakers of British English) have it close behind the upper front teeth.

4. Alveolar

(Tongue tip or blade and the alveolar ridge.) Again there are two possibilities in English, and you should find out which you use. You may pronounce words such as tie, die, nigh, sigh, zeal, lie using the tip of the tongue or the blade of the tongue.

5. Retroflex

(Tongue tip and the back of the alveolar ridge.) Many speakers of English do not use retroflex sounds at all. But some speakers begin words such as rye, row, ray with retroflex sounds.

6. Palato-Alveolar

(Tongue blade and the back of the alveolar ridge.) Say words such as shy, she, show.

7. Palatal

(Front of the tongue and hard palate.) Say the word you very slowly sothat you can isolate the consonant at the beginning.

8. Velar

(Back of the tongue and soft palate.) The consonants that have the place of articulation farthest back in English are those that occur at the end of hack, hag, hang.

THE ORO-NASAL PROCESS

Consider the consonants at the ends of rang, ran, ram. When you say these consonants by themselves, note that the air is coming out through the nose. In the formation of these sounds in sequence, the point of articulatory closure moves forward, from velar in rang, through alveolar in ran, to bilabial in ram.

MANNERS OF ARTICULATION

Stop

(Complete closure of the articulators involved so that the airstream cannot escape through the mouth.) There are two possible types of stop.

Oral stop If, in addition to the articulatory closure in the mouth, the soft palate is raised so that the nasal tract is blocked off, then the airstream will be completely obstructed.

This kind of sound occurs in the consonants in the words pie, buy (bilabial closure), tie, dye (alveolar closure), and kye, guy (velar closure).

Nasal stop If the air is stopped in the oral cavity but the soft palate is down so that air can go out through the nose, the sound produced is a nasal stop.

Although both the nasal sounds and the oral sounds can be classified as stops, the term stop by itself is almost always used by phoneticians to indicate an oral stop, and the term nasal to indicate a nasal stop.

Fricative

The mechanism involved in making these slightly hissing sounds may be likened to that involved when the wind whistles around a corner. The consonants in fie, vie (labiodental), thigh, thy (dental), sigh, zoo (alveolar), and shy (palato-alveolar) are examples of fricative sounds.

The higher-pitched sounds with a more obvious hiss, such as those in sigh, shy, are sometimes called sibilants.

Approximant

In saying the first sound in yacht, the front of the tongue is raised toward the palatal area of the roof of the mouth, but it does not come close enough for a fricative sound to be produced. The consonants in the word we (approximation between the lips and in the velar region) and, for some people, in the word raw (approximation in the alveolar region) are also examples ofapproximants.

Lateral (Approximant)

Say the word lie and note how the tongue touches near the center of the alveolar ridge. Prolong the initial consonant and note how, despite the closure formed by the tongue, air flows out freely, over the side of the tongue. Because there is no stoppage of the air, and not even any fricative noises, these sounds are classified as approximants.

Additional Consonantal Gestures

In this preliminary chapter, it is not necessary to discuss all of the manners of articulation used in the various languages of the world—nor, for that matter, in English. But it might be useful to know the terms trill (sometimes called roll) and tap (sometimes called flap). This kind of combination of a stop immediately followed by a fricative is called an affricate, in this case a palato-alveolar

(or post-alveolar) affricate. There is a voiceless affricate at the beginning and end of the word church. The corresponding voiced affricate occurs at the beginning and end of judge.

To summarize, the consonants we have been discussing so far may be

described in terms of five factors:

1. state of the vocal folds (voiced or voiceless);

2. place of articulation;

3. central or lateral articulation;

4. soft palate raised to form a velic closure (oral sounds) or lowered (nasal

sounds); and

5. manner of articulatory action.

Thus, the consonant at the beginning of the word sing is a (1) voiceless, (2) alveolar, (3) central, (4) oral, (5) fricative; and the consonant at the end of sing is a (1) voiced, (2) velar, (3) central, (4) nasal, (5) stop.

THE WAVEFORMS OF CONSONANTS

At this stage, we will not go too deeply into the acoustics of consonants, simply noting a few distinctive points about their waveforms. The [ h ] that follows this vowel is very short, with hardly any voiceless interval. After the vowel in how, there are some further very short actions. There is hardly any closure for the [ t ], and the vowel in to has only a few vocal fold pulses, making it much shorter than any of the other vowels in the sentence. The fricative [ f ] at the beginning of fish is a little less loud (has a slightly smaller amplitude) than the fricative at the end of this word.

THE ARTICULATION OF VOWEL SOUNDS

In the production of vowel sounds, the articulators do not come very close together, and the passage of the airstream is relatively unobstructed. We can describe vowel sounds roughly in terms of the position of the highest point of the tongue and the position of the lips.

As you can see, in all these vowel gestures, the tongue tip is down behind the lower front teeth, and the body of the tongue is domed upward. Check that this is so in your own pronunciation.

Accordingly, these vowels are called front vowels. The tongue is fairly close to the roof of the mouth for the vowel in heed (you can feel that this is so by breathing inward while holding the target position for this vowel), slightly less close for the vowel in hid (for this and most other vowels it is difficult to localize the position by breathing inward; the articulators are too far apart), and lower still for the vowels in head and had.

These vowels are classified as back vowels. The body of the tongue is highest in the vowel in food (which is therefore called a high back vowel) and lowest in the first vowel in father (which is therefore called a low back vowel). The vowel in good is a mid-high back vowel.

THE SOUNDS OF VOWELS

Studying the sounds of vowels requires a greater knowledge of acoustics than we can handle at this stage of the book. We can, however, note some comparatively straightforward facts about vowel sounds. Vowels, like all sounds except the pure tone of a tuning fork, have complex structures. We can think of them as containing a number of different pitches simultaneously.

Another way of minimizing the sound of the vocal fold vibrations is to say the vowels in a very low, creaky voice. It is easiest to produce this kind of voice with a vowel such as that in had or hod. Some people can produce a creakyvoice sound in which the rate of vibration of the vocal folds is so low you can hear the individual pulsations.

SUPRASEGMENTALS

Vowels and consonants can be thought of as the segments of which speech is composed. Together they form the syllables that make up utterances. Superimposed on the syllables are other features known as suprasegmentals. These include variations in stress and pitch. Variations in length are also usually considered to be suprasegmental features, although they can affect single segments as well as whole syllables.

The pitch of a sound is an auditory property that enables a listener to place it on a scale going from low to high, without considering its acoustic properties. In practice, when a speech sound goes up in frequency, it also goes up in pitch. For the most part, at an introductory level of the subject, the pitch of a sound may be equated with its fundamental frequency, and, indeed, some books do not distinguish between the two terms, using pitch for both the auditory property and the physical attribute.