2. The Acoustic aspect of speech sounds.

Acoustically, all speech sounds are physical phenomena, produced by means of vibration of vocal cords. The amount of vibrations per second is called frequency. On the perceptive level the frequency determines voice height and makes an acoustic base of a speech melody. Sounds can be periodic and non-periodic. If vibrations are periodic we hear musical tone and if vibrations are non-periodic we hear noise.

The sound has some physical characteristics. First of them has been already mentioned. It is frequency, or quantity of fluctuations per second. Frequency of a sound depends on certain physical factors of the mechanism that produces these fluctuations or vibrations - from mass, force and duration. Male voices are lower than female partially thanks to the fact that their vocal cords are longer and thicker.

The second physical characteristic of a sound is intensity. Intensity of sounds of speech depends on the amplitude of fluctuations. Changes in intensity are associated with word stress or with accent in those languages which have dynamic system of stress. Intensity is measured in Decibels. In perceptive level it is associated with loudness of pronunciation

Each sound possesses its own duration or length. The length of a sound is determined by the duration of fluctuations or vibrations. The length is measured in milliseconds.

One more aspect of speech sounds which should be mentioned is a linguistic aspect.

Segmental sounds and prosodic characteristics are linguistic phenomena. Representing language units in real speech, they carry out certain linguistic functions. They make or constitute significant units - morphemes, words, word forms, statements or utterances. Sounds of speech and prosodic characteristics serve to distinguish those units which they form, as our intercourse or speech act is possible only when the sounds can be opposed one to another for distinction of words, word forms and statements. At the same time it allows the listener to percept and distinguish them as concrete words, word forms or statements. The linguistic aspect of speech sounds is also called functional aspect.

3. Functional aspect of sounds of speech. The theory of a phoneme.

However, to classify and describe speech sounds as concrete units of language it is not enough to possess the knowledge of organs of speech and be aware of some ways of sound production. Why!

Really, when we speak about sounds of language the term "sound" can be interpreted in two different ways. So, for example, sounds [t] and [d] represent two different sounds of English language, and they have their own distinctive features which help to differentiate the words in which they are used: tie - die, sat - sаd. The similar phenomenon can be observed in Russian language as well a cat - code, tom-dom. However if consider the realization of the sound {t} in the following examples - let us and let them, it can be clearly seen or to be more exact heard that the first sound is alveolar, and the second is dental. Thus, we may claim that in this very example we deal with two different sounds again and consequently the idea of a sound or the very concept of it, showed in both examples above, is quite different.

To avoid such ambiguities, linguists operate with 2different terms: a phoneme and allophone. The first one means “sound” in its contrastive sense, and the second is used in connection with sounds that are variants of the phoneme, that occur in different position in the word (like in the second example).

The phoneme is the smallest comparative unit of a language which exists in the speech of all people belonging to the same language community, and is realized in the form of speech sounds which are in opposition to other phonemes of the same language and serve to change the meaning of morphemes and words.

The term allophone - is used in relation to sound variants of a phoneme, i.e. to the variants that represent the realization of a phoneme in speech. They usually are in different positions in a word and can not contrast with each other or change the meaning of the word. The distinction between the allophones of one and the same phoneme depends on a phonetic context.

I do believe that I won’t open a secret to you if I say that there are different definitions of a phoneme and they differ from each other greatly.

The materialistic view on the phoneme was presented by the Soviet linguist Lev Владимировичем Shcherba. According to Shcherba’s theory, the phoneme is a functional, abstract and material unit.

The Soviet Encyclopaedic Dictionary contains the following definition - the phoneme is a unit of language that helps to differentiate and identify morphemes and words. The phoneme can be determined as a set of distinctive features. Thus in English words tear and dear two different phonemes t and d may be differentiated and their distinctive features are based on the contrast voiced/voiceless .

The linguistic encyclopaedic dictionary contains the following definition: the phoneme is the basic insignificant unit of a language connected with distinctions of a meaning only indirectly. Carrying out perceptive and significant functions in the text, phonemes in the system of a language are in opposition to each other.

Akhmanova dictionary of linguistic terms says: the phoneme is the shortest unit of a spoken sounding language, representing by itself the certain set of simultaneously realized differential features and capable of distinguishing sound covers of different words and morphemes.

Vladimir Vasil'ev supports the theory of the phoneme which have been put forward by Shcherba, pointing out that the three aspects of the phoneme represent “dialectic unity and define one another and are, thus, interdependent”. In the his definition of the phoneme Васильев specifies that the phoneme is the smallest (further indivisible) unit of a language that exists in the speech of all the members of a given language community as such speech sounds which are capable of distinguishing one word of the same language or one grammatical form of a word from another grammatical form of the same word.

Now. Let’s have a more closer look at the three main aspects of the phoneme.

Firstly, the phoneme is a functional unit. It means, that being opposed to other phonemes in one and the same phonetic context, the phoneme is capable of differentiating the meaning: for example pie-tie, bath - path, light - like.

Sometimes the opposition of phonemes serves to distinguish the meaning of the whole phrase: He was badly heard and He was badly hurt.

Taking everything mentioned above into consideration we may definitely say that the phoneme carries out distinctive function i.e. serves to differentiate the meaning.

Secondly, the phoneme is material, real and objective. It means, that it is realized in speech of all English-speaking people in the form of speech sounds, its allophones. The allophones that do not undergo any changes in the chain of speech are called principle. Thus, for example, the phoneme d in isolation (without any phonetic context) is plosive, forelingual, apical, alveolar, lenis phoneme in such words as: door, darn, down. On the other hand, always there are rather predicted changes in the articulation of allophones in the speech flow under the influence of the neighbouring sounds in various phonetic situations. Such allophones are called subsidiary. Thus, for example, it is possible to observe the articulatory changes of the above-mentioned phoneme in various phonetic contexts: slightly palatalised variant before vowels and j: deal, day, did, did you; sonorant and plosive before m and n: sudden, admit, could not, could meet.

Thus, allophones of the same phoneme may possess similar articulatory features and at the same time can show serious phonetic distinctions. Compare: D in door, darn and in dwelling, dwarf.

Allophones of the same phoneme are grouped in functionally similar groups in which they are opposed not each other but to the members of other groups.

Allophones of the same phoneme never occur in the same phonetic context.

Allophones of the same phoneme, doesn’t matter how greatly their articulation varies, function as one and the same linguistic unit.

Naturally native speakers do not notice any difference between allophones of the same phoneme. At the same time, they subconsciously realize, that allophones of each phoneme have certain distinctive features that make this very phoneme functionally different from all other phonemes of the same language. Such set of relevant articulatory features is called the invariant of the phoneme.

Articulatory features which form the invariant of the phonemes are called distinctive or relevant. To allocate distinctive function of a phoneme, it is necessary to oppose it to other phonemes in the same phonetic context. If the opposed sounds have one articulatory difference and this difference causes change in the meaning of a word, such difference is called relevant. For example, words port and court: the only difference is in the first consonant and the only articulatory difference between these consonants is that the first one is bilabial, and the second is backlingual. Hence, the difference is relevant.

Those features that do not reveal any difference in meaning are called irrelevant or non-distinctive. For example, in English it is impossible to oppose aspirated sound to a non-aspirated in the same phonetic context to create a difference in he meaning.