Aspect of Speech Sounds

Lecture 2. Articulatory and Physiological

To analyse a speech sound physiologicaly and articulatorily some data on the articulatory mechanism and its work should be introduced. Speech is impossible without the following four mechanisms:

(1) thepower mechanism,

(2) the vibrator mechanism,

(3) the resonator mechanism,

(4) the obstructor mechanism.

The power mechanism (Fig. 2) consists of the diaphragm (1), the lungs (2), thebronchi (3), the windpipe (or trachea) (4), the glottis (5), the larynx (6), the mouth cavity (7), and the nasal cavity (8).

Thevibrator mechanism (the voice producing mechanism) consists of thevocal cords, they are in the larynx, or voice box. The vocal cords are two horizontal folds of elastic tissue. They may be opened or closed (completely or incompletely). The pitch of the voice is controlled mostly by the tension of the vocal cords. Voice produced by the vocal cords vibration is modified by the shape and volume of the air passage.

Thoroughacoustic investigations show that besides the vocal cords there are two more sources that participate in the production of speech sounds: (a) the turbulent noise, which results from some constriction in the flow оf air and (b) the impulse wave, which is formed when the complete obstructionto the flow of air in the mouth cavity is suddenly broken. These sources of speech sounds may work separately or simultaneously. For example: (1) the vocal cords produce vibrations in the articulationof vowel sounds, (2) the turbulent noise helps to produce voiceless constrictive consonants, such as /f, s, ς/, (3) the impulse source helps to producevoiceless plosive consonants, such as /p, t, k/.

The two sources — vocal and turbulent participate in the production of voiced constrictive consonants, such as /v, z, 3/, the vocal and impulse sources participate in the production of voiced plosive con­sonants, such as /b, d, g/.

The resonator mechanism (Fig. 3) consists of the pharynx (2), the larynx (4), the mouth cav­ity (1), and the nasal cavity (3).

The obstructor mechanism (Fig. 4) consists of the tongue (1: a — blade with the tip, b — front, с — back or dorsum); the lips (2), the teeth (3), the soft palate with the uvula (4), the hard palate (5), the alveolar ridge (6).

It should be borne in mind that the four mechanisms (the power, the vibrator, the resonator and the obstructor mechanisms) work si­multaneously and that each speech sound is the result of the simultaneous work of all of them.

Fig.3

Fig. 4

The air, which is necessary for the production of the speech so­unds, is pushed out of the lungs. The lungs take in air rapidly and let out slowly. Most speech sounds are made by using the air which id pushed out of lungs.

From the lungs the air gets into the bronchial tubes and then into the trochea, at the top of which there is the larynx with the vocal cords. The larynx of a man is larger than that of a woman and can be easily seen as projecting lump. The space between the vocal folds is called the glottis. The vocal folds vibrate about 130 times for a man's voice and about 230 times for a woman's voice each second. Variations in the speed (frequency) of the vibrations of the vocal cords produce changes of pitch: the higher the frequency, the higher the pitch of the sound produced.

Longer and larger vocal cords produce slower vibrations, i.e. lower frequency and lower pitch. Consequently voices of men are much deeper in pitch than those of women.

The area above the glottis is called the supra-glottal vocal tract. It consists of the pharynx, the mouth and the nasal cavities. The mouth and the nasal cavities are separated by the hard palate and the soft palate with the uvula.

The soft palate, or velum, can move to the pharynx wall and block off the nasal cavity — velic closure, it is part of the articulation of all oral consonants.

When the soft palate is pressed against the back part of the tongue it is a velar closure, e.g. /k, g/ have both — a velic and a velar closure; /ŋ/ is a nasal sound, it is pronounced with the velar closure, the velic closure does not take place in its production.

The uvula is at the back of the soft palate, neither English, nor Russian have uvular articulation.

The bulk of the tongue can be approximately divided into front part with the blade and the tip, middle part, and back part with the root. Some phoneticians call the whole upper surface of the tongue “dorsum”.

In the production of English and Russian forelingual consonants the tip of the tongue may occupy a number of positions. It is raised against the upper teeth ridge in the articulation of the English /t, d, s, z, ς, 3, θ, ð, tς, dЗ, n, l/ and the Russian/л, л',ш, ш',р, р',ж/ — apical position. It is passive and lowered in the articulation of the Russian /т, т', д, д', н, н', с, с', з, з', ч', ц/ — dorsal position, the blade of the tongue takes part in their articulation. The tip of the tongue is against the back slope of the teeth ridge (a depression is formed in the blade of the tongue) in the articulation of the English /r/ — cacuminal position. The tip of the tongue vibrates against the alveolar ridge in the articulation of the Russian /p/ и /р'/.

When the soft palate is raised and forms a closure against the pharynx wall, the entrance to the nasal cavity is shut off.

Most speech sounds are pronounced with the soft palate raised, they are called oral. When the soft palate is lowered the air passes out through the nasal cavity, it happens when normal breathing takes place and when nasal sounds are produced, e.g. English /m, n, ŋ/, Russian /м, м', н, н/.

The oral cavity begins with the lips: upper and lower lip. They can be rounded, as for /w/, protruded, as for the Russian /y/, spread, as for /i:/. The lower lip may move close to the upper teeth, as for /f, v/. The two lips can close to block the air stream, as for bilabial /p, b, m/.

The teeth act as obstacles to the air stream. The upper teeth are the most important for the articulation of dental, or dorsal, — the blade of the tongue is against the upper teeth, alveolar /t, d, 1, s, z, n/, interdental /θ, ð/, labiodental /v/. The alveolar ridge can be felt with the tip of the tongue as a corrugated ridge just behind the upper front teeth.

The hard palate can be felt with the tip of the tongue, it is behind the alveolar ridge. In the articulation of the sound /j/ the tongue makes a movement towards the hard palate.

The centre of the tongue can be grooved along mid-line, the sides raised, e.g. /s, z/.

The front of the tongue can be raised to the hard palate, e. g. English /j/.

The back of the tongue can be raised to the velum, e.g. the Russian /x/, it is pressed against the velum, e.g. the Russian /к, г/ and the English /k, g/.

The ability to detect the movements made by the tongue diminishes towards the back of the tongue.

Articulatory differences between vowels, consonants and sonorants depend on the three articulatory criteria. They are:

(1) the presence or absence of an articulatory obstruction to the air
stream in the larynx or in the supra-glottal cavities;

(2) the concentrated or diffused character of muscular tension;

(3) the force of exhalation.

On the basis of these criteria consonants may be defined as sounds in the production of which (a) there is an articulatory obstruction to the air stream (complete, incomplete, the combination of the two /tς, dЗ/ intermittent; (b) muscular tension is concentrated in the place of obstruction; (c) the exhaling force is rather strong.

Vowels may be defined as sounds in the production of which (a), there is no articulatory obstruction to the air stream; (b) muscular tension is diffused more or less evenly throughout the supra-glottal part of the speech apparatus; (c) the exhaling force is rather weak.

Sonorants are sounds intermediate between noise consonants and vowels because they have features common to both. The obstruction is complete or incomplete but not narrow enough to produce noise. Muscular tension is concentrated in the place of obstruction, but the exhaling force is rather weak. English sonorants are: /m, n, ŋ, 1, w, r, j/.

Дата добавления: 2014-01-06