Speech sounds are of complex nature and have 4 different aspects, which are closely connected: the articulatory aspect, the acoustic aspect, the auditory aspect and the linguistic aspect. The ability to form language units is not the only property of the sound medium. In addition to it, the sound substance has its own independent properties as a physical phenomenon. Moreover, it is a product of human activity. Being created by the speaker, the sound substance indicates the speaker’s personality (sex, age, individual features), reveals his physiological and emotional state, geographical origin, education, social status and so on. Sound phenomena have different aspects.
Every act of speech presupposes the presence of a person who speaks and a person who listens. The speaker produces sounds, the sounds travel through the air to the listener in the form of complex combinations of sound waves, the listener hears and interprets them. Communication is possible only because the speaker and the listener interpret the sounds as units of the same language.
The articulatory aspect. Speech sounds are products of human organs of speech. They result from the activities of the diaphragm, the lungs, the bronchi, the trachea, the larynx with the vocal cords in it, the pharynx, the mouth cavity with the speech organs in it and the nasal cavity. Sound production is impossible without respiration, which consists of two phases- inspiration and expiration. Speech sounds are based chiefly on inspiration, though in some African languages there are sounds produced by inspiration.
Expiration, during which speech sounds are produced, is called phonic expiration. It is distinct from quiet breathing. In phonic expiration the air comes from the lungs not freely but in spurts, because during speech the air passage is periodically blocked by the speech organs. Therefore in speech, expiration lasts much longer than inspiration, whereas in quite breathing inspiration and expiration each take about the same period of time.
The lungs supply the necessary air-pressure and regulate its force. For example, the air pressure is greater on the peak of the syllable and it is less on its margins.
Sound production actually takes place in the larynx, the pharynx and the oral and nasal cavities. The air-stream coming from the lungs undergoes important modifications in them.
The other part of sound-production is articulation. The movements of speech organs modify the shape, size and volume supralanryngeat cavities. As a result, a vowel sound of a certain quality is produced.
When there is an obstruction to the air-stream in the supralanryngeat cavities, a noise is produced. The character of the noise (friction or plosion) depends on the type of obstruction (a constriction or a complete closure) and determines the particular quality of a consonant. When an obstruction is created and the vocal cords vibrate, a voiced consonant is produced. When the vocal cords do not vibrate, the result is a voiceless consonant.
Thus there are main sources of vibration in the production of speech sounds – the vocal cords and various kinds of obstruction.
The acoustic aspect. Sounds can be analysed from the acoustic point of view. Like any other sound of nature speech sounds exist in the form of sound waves and have such physical properties as frequency, intensity, duration and spectrum.
A sound wave is created by a vibration which may be periodic or non-periodic, simple or complex. The number of vibrations per second is called frequency.
The complex range of intensified frequencies which form the quality of a sound is called the acoustic spectrum of the sound.
Intensityof speech sounds depends on the amplitude of vibration. Changes in intensity are associated with stress in those languages which have dynamic stress. Intensity is measured in decibels.
The auditory aspect. Speech sounds may also be analysed from the point of view of perception. It involves the activity of our hearing mechanism, which can be considered in two ways. On the one hand, it is a physiological mechanism, which reacts to acoustic stimuli. On the other hand, it is also a psychological mechanism, which selects from the great amount of acoustic information only that which is linguistically important. The human ear transforms mechanical vibrations of the ear into nervous stimuli and transmits them to the brain. The listener hears the acoustic features of fundamental frequency, format frequency, intensity and duration in terms of four perceptible categories of pitch, quality, loudness and length.
The linguistic aspect. Segmental sounds and prosodic features are linguistic phenomena. Representing language units in actual speech, they perform certain linguistic functions. They constitute meaningful units- morphemes, words, word-forms, utterances. All the words of a language consist of speech sounds which are grouped and arranged in the way specific for the language and which are unified by stress. All the utterances consist of words and of sounds. They are characterized by certain pitch-and-stress patterns, temporal features, rhythm.
The linguistic aspect of speech sounds is also called functional or social aspect, because of the role which sound matter play in the functioning of language as a social phenomenon. Segmental sounds and prosodic features of speech perform constitutive, distinctive and identificatory functions.
The relations between the articulatory, acoustic, auditory and linguistic aspects of speech sounds can be presented in the following way:
| Articulatory aspect
|| Acoustic aspect
|| Auditory aspect
|| Linguistic aspect
| Vibration of the vocal cords
|| Fundamental frequency
|| Prosody (melody, stress)
| Different positions and movements of speech organs
|| Formant frequencies
|| Quality (timbre)
|| Phoneme, prosody (stress)
| The amplitude of vibrations
|| Prosody (stress)
| The quantity of time during which the sound is pronounced
|| Prosody (tempo, rhythm)
1. What sciences is phonetics connected with?
2. What are the main branches of phonetics?
3. What is the subject of special and general phonetics?
4. What is a phonetic system of a language?
5. What levels does the phonetic system of a language consist of?
6. What are segmental units of the language?
7. What are prosodic units of the language?
8. What subsystems do the segmental units form?
9. What subsystems do the prosodic units form?
10. What are the stages of human speech formation?
11. What aspect do sounds have?
12. What phases does respiration consist of?
13. What are the main sources of vibration in the production of speech sounds?
14. What is frequency?
15. What is spectrum?
16. How is intensity measured?
17. What are the perceptible features of auditory aspect of speech sounds?
18. What meaningful units do segmental sounds and prosodic features constitute?