Phonetics deals with the sound substance of language. This substance may be studied from different points of view and according to this points one may speak about different branches of phonetics.
1) From the point of view of the specification of the object of the study phonetics may be special and general. The former is concerned with the study of the phonetic system of a concrete language. General phonetics is concerned with the study of man's speech sounds on the whole. It establishes types of speech sounds, which exist in different languages, the ways they are produced and the role they play when forming and expressing thoughts. The result of such study is a number of theories concerning human languages as an abstraction, e.g. phoneme theory.
2) From the point of view of the time concerned in the phonetic study phonetics may be descriptive and historical. Descriptive phonetics studies the phonetic system in a stative form at a particular period of time, studies the phonetic system synchronically. Historical phonetics studies the system in it's historical development, diochronically. It studies written documents and compares the spelling and pronunciation of one and the same word in different periods of the language development.
3) Phonetics may be studied from the point of view of the sphere of linguistic study. Divided into theoretical and practicalphonetics. Theoretical phonetics applies the theories worked out by general phonetics to the language it analysis. It deals with functioning of phonetic units in the language as a system. Practical phonetics (applied phonetics) is all the practical applications of phonetics, which are especially important when learning a certain language. Practical phonetics deals with functioning of phonetic unit in speech.
4) From the point of view of correlation between different languages. There is one more important part of phonetics called comparative phonetics. It compares phonetic systems of two or more languages and not only kindred ones.
5) From the point of view of the aspects of a speech sound there may be the following division of phonetics. Investigations show that there are 4 aspects of a speech sound:
· articulatory aspect
· auditory aspect
· acoustic aspect
· functional aspect (linguistic, social)
Articulatory phonetics studies speech sounds from the point of view of their articulation and in connection with the organs of speech by which they are produced.It employs experimental methods.
Auditory phoneticsdeals with the study of man's perception of sound phenomena. It also employs experimental methods.
Articulatory and auditory phonetics are sometimes combined into one branch called physiological phonetics. Because sound production and sound perception are physiological processes.
Acoustic phonetics investigates acoustic properties of sounds, such as quality, length, intensity, pitch and others. It also employs experimental methods.
Phonology (functional phonetics) is a purely linguistic branch, dealing with the functional aspect of sound phenomena. It discovers segmental and prosodic features that have a differentiantial value in a language. It establishes the system of phonemes and prosodies. The basis of phonology is the phoneme theory, established by Ivan Andreevich Baudouin de Courtenay in the years between 1868 and 1881. The theory was developed by his pupils, such as Sherba, Grushevskiy and some others. Phonology was founded in Prague by such linguists as Nikolay Trubetskoy, Roman Jakobson and others. The branch was launched in 1923. Trubetskoy claimed that phonology should be separated from phonetics. According to him phonetics is a biological science which is concerned with physical and physiological characteristics of speech sounds, while phonology is a linguistic science and is concerned with the social function of phonetic phenomena. The majority of Russian phoneticians do not consider it logical and to separate form from function and to exclude phonetics from the linguistic science.
All the above branches of phonetics are closely connected since the object of their study, that is speech sounds, is the close unity of acoustic, articulatory, auditory and linguistic aspects.