Chapter 1 Articulation and Acoustics

Bab 1 : Articulation and Acoustics

1.    SPEECH PRODUCTION.

How speech sounds are made? The speech sounds are made by movements of the tongue and the lips. In order to make speech sounds can be heard and recognized the gestures of the tongue and lips are made audible.

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.

Figure 1.1

Figure 1.1 shows a series of frames from an x-ray pictures of a speaker saying on top of his deck.

The tongue has been outlined to make it clearer. The lettering to the right of the frames shows, very rudely, the sounds being produced. The individual frames in the figure show that the tongue and lips move quickly from one position to another.

When you talk, air from the lungs goes up the windpipe and into the larynx, at which point it must pass between two small muscular folds called the vocal folds. The vocal folds, also known populary as a vocal cords which composed of twin infoldings of mucous membrane stretched horyzontally across the larynx.

            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.

In order to hear the difference between a voiced and a voiceless sound, try saying a long ‘v’ sound, which we will symbolize as [ vvvvv ]. Now compare this with a long ‘f ’ sound [ fffff ], saying each of them alternately [ fffffvvvvvfffffvvvvv ]. Both of these sounds are formed in the same way in the mouth. The difference between them is that [ v ] is voiced and [ f ] is 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 shape of the vocal tract is a very important factor in the production of speech, and we will often refer to a diagram of the kind that has been superimposed on the photograph.

Figure 1.2  vocal tract

Learn to draw the vocal tract by tracing the diagram in this figure.

The parts of the vocal tract that can be used to form sounds, such as the tongue

and the lips, are called articulators. The four main components of the speech mechanism are the airstream process, the phonation process, the oro-nasal process, and the articulatory process. The airstream process includes all the ways of pushing air out that provide the power for speech. For the moment, we have considered just the respiratory system, the lungs pushing out air, as the prime mover in this process. 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.

2.    SOUND WAVES

            Sound waves are longitudinal waves that must pass through a medium, such as air. Sound waves are produced by all vibrating objects.

            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. Thus, 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 that one was said on a higher pitch or that one of them was spoken more loudly.

3.    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. They make the gestures required for speech by moving toward the articulators that form the upper surface.

The principal parts of the upper surface of the vocal tract are alveolar ridge, hard palate, soft palate, velum, velic closure.

The principal terms for the particular types of obstruction are :

·         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.

·         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.

·         Dental

            (Tongue tip or blade and upper front teeth.) Say the words thigh, thy.

·         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.

·         Retroflex

            (Tongue tip and the back of the alveolar ridge such as rye, row, ray with retroflex sounds.

·         Palato-Alveolar

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

·         Palatal

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

·         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.

4.    THE ORO-NASAL PROCESS

            Consider the consonants at the ends of rang, ran, ram. When you say these consonants rang, ran, ram. the air is coming out through the nose. In this case, the air is prevented from going out through the mouth but is able to go out through the nose because the soft palate, or velum, is lowered. When it is lowered and there is an obstruction in the mouth, we say that there is a nasal consonant. Raising or lowering the velum controls the oro-nasal process, the distinguishing factor between oral and nasal sounds.

5.    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. Pressure in the mouth will build up and an oral stop will be formed.

·         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 the term stop may be defined so that it applies only to the prevention of air escaping through the mouth, it is commonly used to imply a complete stoppage of the airflow through both the nose and the mouth.

6.    THE ARTICULATION OF VOWEL SOUNDS

We can describe vowel sounds roughly in terms of the position of the highest point of the tongueand the position of the lips. In the first four vowels, the highest point of the tongue is in the front of the mouth. these vowels are called front vowels.

            Lip gestures vary considerably in different vowels. They are generally closer together in the mid-high and high back vowels (as in good, food), though in some forms of American English this is not so. Look at the position of your lips in a mirror while you say just the vowels in heed, hid, head, had, father, good, food. You will probably find that in the last two words, there is a movement of the lips in addition to the movement that occurs because of the lowering and raising of the jaw. This movement is called lip rounding. It is usually most noticeable in the inward movement of the corners of the lips. Vowels may be described as being rounded (as in who’d) or unrounded (as in heed).

the targets for vowel gestures can be described in terms of three factors: 

1. the height of the body of the tongue.

2. the front–back position of the tongue. 

3. the degree of lip rounding.

7.    THE SOUNDS OF VOWELS

            Vowel sounds may be said on a variety of notes (voice pitches), but they are distinguished from one another by two characteristic vocal tract pitches associated with their overtones. One of them (actually the higher of the two) goes downward throughout most of the series heed, hid, head, had, hod, hawed, hood, who’d and corresponds roughly to the difference between front and back vowels.

There is the pitch at which the vowel is actually spoken, which depends on the pulses being produced by the vibrating vocal folds; and, quite separate from this, there are overtone pitches that depend on the shape of the resonating cavities of the vocal tract. These overtone pitches give the vowel its distinctive quality. Normally, one cannot hear the separate overtones of a vowel as distinguishable pitches. The only sensation of pitch is the note on which the vowel is said, which depends on the rate of vibration of the vocal folds. But there are circumstances in which the overtones of each vowel can be heard.

The characteristic overtones are called the formants of the vowels, the one with the lower pitch (distinguishable in creaky voice) being called the first formant and the higher one (the one heard when whispering) the second formant.

8.    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. Superimpose 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. Variations in stress are used in English to distinguish between a noun and a verb,

as in (an) insult versus (to) insult. Say these words yourself, and check which syllable has the greater stress.

Pitch of the voice is what you alter to sing different notes in a song. Frequency is a technical

term for an acoustic property of a sound—namely, the number of complete repetitions

(cycles) of a pattern of air pressure variation occurring in a second.

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.