Если у вас возникли сложности с курсовой, контрольной, дипломной, рефератом, отчетом по практике, научно-исследовательской и любой другой работой - мы готовы помочь.
Предоплата всего
Подписываем
Lecture 3
Theme: The Articulatory and Acoustic Aspects of the English Speech Sounds.
Plan:
Objectively, sound is a physical phenomenon, a kind of moving energy generated by some vibrating body, such as a string, a tuning fork or the vocal cords, set into vibration by the application of some external force.
Thus, in order to produce sound some physical body must be set into vibration, or oscillatory motion, by the application of some external force — a blow must be struck, or the pressure of air applied.
When such a force is applied, the physical body begins to oscillate — to move forward and backward.
When the vibrator moves forward it pushes the particles (or molecules) of air (or some other propagating medium) which are next to it and displaces them. The displaced layer of particles displaces the next layer, and the original pressure is transmitted through the air.
Thus when the vibrator moves forward, it compresses, or condenses the air — that is, the spaces between the air molecules become smaller.
When the pressing force has spent itself, the displaced particles rebound to their original positions because of the elasticity of air and overshoot these positions because of the ' momentum. On the rebound to their original positions the particles of air produce rarefactions behind them — that is, the space between two neighboring particles is increased.
These alternating waves of condensation and rarefaction are sound waves. They move outward from the source of disturbance not in circles, as in the case of waves on the surface of water, but in concentric, spheres of alternating condensation and rarefaction. Besides the mechanical oscillatory motion of a physical body (a string, a tuning fork), there is another way of producing sound waves, or alternating waves of condensation and rarefaction — that is by periodic alternation of the pressure of air. The action of the siren is based upon this principle. A strong stream of air is periodically interrupted by a special device, with the result that the stream of air escapes in rhythmical puffs which produce alternating condensations and rarefactions of the atmospheric air.
Sound has a number of physical properties which all exist and manifest themselves simultaneously; each of them can be singled out and separated from the others only for purposes of analysis.
The first of these properties is frequency, which is the number of vibrations per second. Sound waves may follow one another at different rates of frequency; therefore the number of vibrations, or cycles, as they are called, per second (cps) varies greatly.
Dependent on the frequency of vibration is the length of the sound wave, i.e. the distance between the point of maximum compression in one wave to the point of maximum compression in the next wave, or, in other words the distance between points having the same phase (position) in two adjacent waves.
Wave length is inversely proportional to the frequency of vibration; the higher the frequency, the shorter the wave length. Our perception of the frequency of repeated pressures on the ear-drum is the pitch of the sound. The greater the frequency, the higher the pitch, and vice versa.
The frequency of sound depends on certain physical properties of the vibrator, such as its mass, length and tension.
The greater the mass of the vibrator, the slower its vibrations, and the lower the pitch (other conditions being equal). Some people's vocal cords are thicker and heavier than those of others and their voices are lower than the voices of those with thinner, lighter vocal cords.
The longer the vibrator, the slower the vibrations, the lower the frequency and the pitch. A man’s voice is lower than a woman's partly because his vocal cords are longer.
The second physical property of sound is intensity, changes in which are perceived primarily as variations in the loudness of sound. The intensity of sound is produced by the amplitude of vibrations, i.e. by the distance to which the air particles are displaced from their position of rest by the application of some external force, or, in other words, by the degree of the condensation of air and by the force of the pressure which the displaced air particles exert on the ear-drum. Naturally, the greater the external force applied to cause vibration, the greater the amplitude of vibration, the greater the intensity of sound, the greater the pressure of the displaced air particles upon the ear-drum, the louder the sound. Intensity as it manifests itself in loudness is measured in decibels (dbs).
If one wants to increase intensity (loudness) of а low pitched sound, he must apply a greater amount of energy.
Closely connected with the frequency and intensity of sound is its composition or complexity. A physical sound that is set into vibration vibrates not only as a whole also in its parts (segmental vibrations).
If we record graphically the simple pendulum-like vibrations of the whole body, the sound curve will have form of a wavy line, called the sine-curve.
The sound wave produced by the vibration of the whole body is called the fundamental. If we record graphics both the vibrations of the whole body and the vibrations its parts, the sound curve thus obtained will have additional little waves on its downward slopes.
Waves produced by the vibrations of the parts of body are called partial waves.
Most sound waves are complex ones i.e. they consist the fundamental and partial waves blended together.
The frequency of the fundamental is lower than that the partial waves. The sound wave which results from the vibrations of the whole body and which have the lowest frequency is perceived as the fundamental tone.
The characteristic partial waves which result from the vibrations of the parts of the vibrating body are perceived as partial tones, or overtones, also called harmonics.
The complex glottal tone can be so modified by us as to produce vowel sounds of various qualities, or tambers.
This is achieved through the action of the resonator mechanism, i.e. by varying the size and shape of the supra-glottal cavities (primarily those of the mouth), which function-as resonating chambers. Thus, the production and differentiation of vowel sounds is based on the acoustic phenomenon called resonance, which consists in the following.
If you strike a tuning-fork, thus making it vibrate, and hold it by the stem, the sound heard by you will be rather weak, faint, but it will last long. If the stem is held on a flat surface, such as a board of some size, the surface will vibrate with the approximate frequency of the fork as long as the vibrating fork is held there. The vibrating area will be larger, therefore a larger volume of air will be set into vibration; thus the sound will be amplified and heard much better, but it will last less time. Such a board is called a sounding-board and its sound amplifying effect is resonance — sounding-board resonance. The sound of strings is amplified in this way.
Thus, when a periodic vibration (force) is applied to an elastic system, the system will tend to vibrate with the frequency of the applied force. The nearer the periodic force is to the natural frequency of the elastic system, the great er will be the resulting amplitude of vibration. When this amplitude is at its maximum, so that the sound is appreciably louder, we have resonance. In other words, resonance occurs whenever there is impressed upon a body the frequency at which it would vibrate if set in motion and then left to itself. Another example:
If a vibrating tuning-fork is placed near another fork with the same frequency, the latter will begin to vibrate also — this is called sympathetic vibration and is also resonance.
Indispensable in phono-acoustics are the concepts of the formants and spectrum of a speech sound. By formants are meant concentrations of energy in certain frequency regions, or bands, characteristic of a particular sound.
The acoustic spectrum of a speech sound is the whole complex range of frequencies of varying intensity which go to make up the quality of this or that particular sound
An acoustic description of a speech sound consists in describing its acoustic spectrum in terms of its formants, determined by means of spectrograph.
Spectrographic analysis has provided not only data for an acoustic description of speech sounds, but also a basis for the latter's acoustic definitions and classification. The first comprehensive acoustic classification of speech sounds based on the spectrographic analysis has been worked out by Roman Jacobson, С G. M. Fant and M. Halle.
The classification is not merely phonoacoustic, it is also a phonemic one, and as the authors claim, it is applicable to all the languages of the world. The acoustic features of speech sounds included in the classification form 12 binary, (or dichotomous) distinctive oppositions.
All these distinctive features are inherent ones, i.e. segmental, and not prosodic, or supra-segmental.
Although acoustic descriptions, definitions and classifications of speech sounds are considered to be more precise than articulatory ones, they are practically inapplicable and, therefore, useless in language teaching. The acoustic features of speech sounds cannot be seen directly or felt by the language-learner; neither can the latter correlate them himself with the positions and movements of his own or his teacher's speech organs and with the resulting auditory impressions. It is no mere chance, therefore, that the authors of such acoustic descriptions, definitions and classifications of speech sounds cannot help correlating them with articulator descriptions. This is the only way of making phono-acoustic descriptions and classifications comprehensible at all to those who themselves have not (and cannot be expected to have) any access to spectrographic analysis or to spectrograms prepared by others. Naturally, these people (and they are in the overwhelming majority) can learn the acoustic definitions of speech sounds only by remembering their articulatory equivalents rather than the peculiarities of the acoustic spectra, e.g. that compact vowels are open ones, that flat means rounded, etc.
There are, however, other fields of the application of phonetics in which acoustic descriptions, definitions and classifications of speech sounds are of great practical and theoretical importance or even indispensable. One of these fields is technical acoustics. Description of speech sounds in terms of formant figures and other spectrographic data is indispensable to the solution of the problem of speech synthesis and machine recognition of speech, as well as to the design and construction of cybernetic machines capable of putting out information in spoken words.
Acoustic descriptions, definitions and classifications of speech sounds are of great theoretical importance also to linguistics. This is the reason why, as has already been mentioned, the acoustic phonemic classification worked out by R. Jacobson, С G. M. Fant and M. Halle is gaining international currency.
Some linguists, however, level a number of criticisms at this classification. Its applicability to all the languages of the world is questioned; its very validity needs experimental verification on a much larger scale; its preciseness and the validity of its basic principle of binary distinctive oppositions are doubted.
The articulatory aspect of the English speech sounds.
Speech sounds are acoustic effects of the articulatory movements and positions of the human speech organs. The articulation of every speech sound and the transition from the articulation of one sound to the articulation of the sound that follows are effected and controlled by the action of the muscles situated in the organs of speech involved. These muscles are activated (contracted and relaxed) by impulses, or "commands" sent from the brain along the efferent nerves.
Some linguists, such as L. V. Shcherba and his disciple and follower M. I. Matusevitch associate the articulatory aspect of speech sounds with their biological aspect. Considered from this point of view, speech is one of the most characteristic and important functions of the human organism, one of the faculties of man that distinguishes him from all other animals. More exactly, speech is a function of the human brain, of man’s central and peripheral nervous systems.
On the one hand, the human brain is the original source of speech, and, on the other, it perceives speech sounds coming from the external world as physical phenomena and interprets them as phonemes carrying meaning.
The processes taking place in the human brain during the production, perception and understanding of speech are extremely complicated and have not yet been fully clarified. They are the province of physiology rather than that of phonetics, and we shall not deal with them. The problem is being successfully tackled by the Soviet school of physiology founded by I. P.Pavlov.
Since speech sound production (phonation) is impossible without the outgoing stream of air from the lungs, the latter are considered by many to be organs of speech: they do not only supply the energy (air-pressure) to produce the spectral component of the sound matter of language, but also regulate the force of the air-pressure and thus produce variations in the intensity of speech sounds, i.e. the force (or intensity) component of the sound matter of language.
According to their main sound-producing functions the speech organs can be roughly, but conveniently, divided into the following four groups:
This division is by no means rigid, because the four mechanisms are not only closely interconnected, but actually also overlap, i.e. the speech organs forming part of one mechanism may form at the same time part of another mechanism and assume the latter's functions in addition to or to the exclusion of their functions as part of a different mechanism.
The functions of the power mechanism consist in the supply of energy in the form of air pressure and in regulating the force of the air-stream. The power mechanism includes the following organs of respiration: (1) the diaphragm, (2) the lungs, (3) the bronchi, (4) the windpipe, or trachea, (5) the glottis (the opening between the vocal cords), (6) the pharynx, (7) the mouth cavity, and (8) the nasal cavity.
The glottis and the three supra-glottal cavities enter into the power mechanism as component parts of the respiratory tract without which breathing and, therefore, life and speech are impossible. But the glottis is simultaneously part of the vibrator mechanism, while the supra-glottal cavities form also the resonator mechanism.
The process of respiration is governed by physical laws. Inhalation (inspiration) takes place because the chest expands due to the action of the diaphragm and chest (or intercostals) muscles. As the result of this expansion, the air pressure in the lungs becomes lower than the pressure of the surrounding atmospheric air, and the latter rushes into the lungs and fills them so that the pressure is equalized.
Then the diaphragm and the chest-muscles relax and the chest resumes its former dimensions; the lungs are contracted, the air-pressure in them becomes greater than the pressure of the surrounding atmospheric air, and the air which is in the lungs rushes out, forming a stream, or a flow of air, which passes through the bronchi, the windpipe, the glottis, and the mouth or nasal cavities. This is exhalation, or expiration. Thus the process of breathing consists of two alternating phases: 1) inhalation (inspiration) and 2) exhalation (expiration).
This process is primarily and fundamentally a biological one, but the second phase — expiration — is utilized for sound-producing purposes as well. Therefore one must distinguish two kinds of breathing: (1) simple, ordinary biological breathing which takes place when we are silent, and (2) sound-producing, or phonatory, breathing.
The air-stream provided by the lungs undergoes important modifications in the upper stages of the respiratory tract before it produces the components of the sound matter of language. First of all, it passes through and thus sets into action the vibrator, or voice-producing, mechanism which is housed in the larynx, or voice-box. As the air is exhaled from the lungs it is fed under pressure into the larynx through the windpipe.
The larynx is a casing formed of cartilage and muscle. It is situated in the upper enlarged end of the trachea. Its forward portion forms the projection in the throat below the chin and is commonly called the Adam's apple.
The larynx is a movable frame of cartilage —a ring-shaped, cricoids, cartilage, on which rests the shield-like, or thyroid, cartilage.
This frame is held in place by membranes and muscles and is lined with mucous membrane. It can rise or fall over the space of about a centimeter, as can be felt with a finger while sounding various vowels.
Inside this frame, extending inward from the right and left walls, there is pair of folds in the mucous membrane shaped like ledges or fleshy lips, with their free edges reaching from front to back near the middle of the larynx. These are called the vocal cords (bands, lips). Their inner edge has a length of about 23 mm. in adult men and about 18 mm. in women.
Along their inner edges these folds contain elastic ligament interspersed with muscle fibre, and, farther, a cone of muscle (the vocal muscle).
The ligament and muscle are attached to the inside front wall of the thyroid near the centre and at the back each fold is attached to -one of a pair of adjustable cartilages called the arytenoids.
These cartilages can be so moved by the attached muscles that by coming together they can bring the inner edges of the vocal cords completely together, or by spreading apart can separate them at the back so as to make a wedge-shaped opening between the vocal cords with the apex in front and extending back between the two cartilages.
This opening through which the breath must issue is called the glottis.
The glottis consists of two parts — the opening between the vocal cords, the cord glottis (glottis proper, or voice glottis) constituting 2/3 of the whole; and the opening between the arytenoids cartilages, called the cartilage, or whispering glottis.
The vocal cords perform a double function: a biological one and a linguistic one, each of which depends on their position and, consequently, on the shape of the glottis.
The action of the arytenoids cartilages is such that both the cord glottis and the cartilage glottis can be opened together. This is the position for breathing and its function is primarily a biological one.
In ordinary breathing the glottis is freely open. In rapid breathing through the mouth it is open to its fullest extent.
The glottis is more open in inhaling than in exhaling.
The linguistic function of this position of the vocal cords consists in providing the source of energy (a supply of air in the lungs) necessary for speech production. In addition to its function as part of the power mechanism, the glottis may function as part of the obstructer mechanism to produce consonantal noises. If the glottis is narrowed during exhalation the friction of breath on the inner edges of the vocal cords may be heard as an [h]-like sound. Because of this, British and American phoneticians, as well as Professor A. L. Trakhterov, consider the English [h] to be a laryngeal, or glottal, consonant and not a pharyngeal one, as other authorities believe it to be.
The phonetic division of consonants into voiceless and voiced ones, phonemically relevant in many languages, is based on the action of the vocal cords as part of the vibrator mechanism.
This action of the vocal cords provides one of the basic and generally accepted principles of consonant classification, although different terms are used by different authors to designate the two classes of consonants distinguished according to this principle. Thus, D. Jones uses the term breathed /breOt/ for certain voiceless consonants, admitting, however, that it is convenient to use the term "breathed" in speaking only of continuant sounds, such as [f, s, 0, f, h], and "voiceless" in speaking of plosive consonants, such as [p, t, k], because it can hardly be said that during the "stop" of a plosive consonant there is a current of air passing between the vocal cords.
This differentiated use of the two terms designating one and the same feature of both continuant and stop consonants (the absence of voice) is not generally accepted, and only the term voiceless is preferred.
Of all the movable organs within the mouth cavity, the tongue is by far the most flexible and is capable of assuming a great variety of positions. Therefore it is the most active resonance-modifier, being responsible for the greatest number of modifications of the shape of the mouth resonator, which ultimately determine different vowel tambers.
It is for this reason that the main two principles of all current articulatory classifications of vowels are based on the movements and positions of the tongue. For such classificatory and descriptive purposes, the surface of the tongue is conventionally divided into several parts, although the tongue itself, a complex muscular structure, does not show obvious sections. A convenient basis for such a division is provided by the fixed organs lying opposite the tongue when it is at rest. In describing and classifying vowels the following parts of the tongue are referred to because of their great importance as resonance-modifiers: (1) the front of the tongue, which lies opposite the hard palate (in Russian phonetic literature it is called the middle of the tongue), (2) the .back of the tongue, which lies opposite the soft palate, and (3) the centre of the tongue, which is the region where the front and the back meet. The tip and blade of the tongue do not play separate roles in vowel production. As the body, or bulk, of the tongue moves forward or backward, i.e. in a horizontal direction, one of the parts of its surface is usually higher than all the other parts, although its actual height from the lowest position and, therefore, the distance between this highest point and the opposite part of the roof of the mouth, may vary, thus marking the simultaneous movement of the tongue in a vertical direction.
This complex movement of the tongue provides a convenient articulator basis for classifying vowels according to two important principles: (1) according to the horizontal (or, to be more exact, forward-backward) movement of the tongue, or, as D. Jones puts it "according to the part of the tongue which is raised highest", and (2) according to the simultaneous vertical movement of the tongue or, as D. Jones puts it "according to the height to which the tongue is raised". These two main principles of vowel classification are generally accepted, although they may be, expressed in different ways, and there may be, differences of opinion as to how many classes of vowels should be distinguished according to these principles, by what terms these classes should be designated and which vowels should be assigned to this or that class.
When the bulk of the tongue moves forward, it is usually its front part which is raised highest, towards the hard palate. Vowel sounds produced with this tongue position are called front vowels, e.g. the English [i:, i, e, ж] and the nuclei of the English diphthongs [w, ei, sa, ai, auj, as well as the Russian vowels [и, э].
The English front vowels [i:] and [i] actually differ from each other not only in length, but also in quality.
One of the causes of the latter difference is the difference in the parts of the tongue which are raised highest in pronouncing [i:] and |i]. In the case of [i:] the highest part of the tongue is defined by D. Jones as the centre of the front, whereas in the case of [i] it is defined by him as the hinder part of the front.
This difference in tongue position necessitates the subdivision of the English front vowels into fully front ([i:, е, æ] and the nuclei of [ei, еэ, ai]) and front-retracted ([i] and the nucleus of [аu]).
This subdivision is especially necessary since the vowels [i:] and [i] represent different phonemes in English mainly because of a difference in quality and not in quantity (although D. Jones considers them variants of one phoneme, both of which he designates by the symbol i).
When the bulk of the tongue moves backwards, it is usually its back part which is raised highest, towards the soft palate. Vowel sounds produced with this tongue position are called back vowels, e.g. the English [a:, o, о:, u:, u, Λ] and the nuclei of [oi, oэ, ou,uэ], as well as the Russian [o, y].
The English back vowels [u:] and [u], like [i:] and [i], actually differ from each other not only in length, but also in quality. As in the case of [i:] and [i], one of the causes of this qualitative difference is the difference in the parts of the tongue which are raised highest in pronouncing [u:] and [u]. In the case of [u:l the highest part of the tongue is defined by D. Jones as the back, whereas in the case of [u]it is defined by him as the fore part of the back.
This difference in tongue position necessitates the subdivision of the English back vowels into fully back ([o, o:, u:]) and back-advanced ([а:, Λ , u] and the nuclei of the diphthongs ou, uэ]).
This subdivision is especially necessary since the vowels [u:] and [u] represent different phonemes in English mainly because of a difference in quality and not in quantity (although D. Jones considers them variants of one phoneme, both of which he designates by the symbol u).
It is very important to know the peculiarities of the articulation basis of the foreign language studied and of that of one's mother tongue. This knowledge is a good aid both in linguistic analysis and in language-teaching; if the learner knows the speech basis of the foreign language it will be easier for him to learn the peculiarities of its sound system and master it.
Sources:
Васильев В.А. "Фонетика английского языка" М; 1970г.
Васильев В.А. Теоретический курс "Фонетика английского языка" М; 1962г.
Леонтьев С.Ф. Теоретический курс английской фонетики. М; 1981г,1988 г.
Соколова М.А., Гинтовт К.П. "Фонетика английского языка". М; 1991г.