It is actually accepted that a vowel is a speech sound made by allowing breath to flow out of the mouth, without closing any part of the mouth or throat (although the lips may move to create the correct sound, as in creating the sound “o”). Letters of the English alphabet that represent vowels: a, e, i, o, u, and sometimes y. The quality of a vowel is known to be determined by the size, volume, and shape of the mouth resonator, which are modified by the movement of active speech organs, that is the tongue and the lips. Besides, the particular quality of a vowel can depend on a lot of other articulatory characteristics, such as the relative stability of the tongue, the position of the lips, physical duration of the segment, the force of articulation, the degree of tenseness of speech organs.
So vowel quality could be thought of as a bundle of definite articulatory characteristics which are sometimes intricately interconnected and interdependent. For example, the back position of the tongue causes the lip rounding, the front position of the tongue makes it rise higher in the mouth cavity, the lengthening of a vowel makes the organs of speech tenser at the moment of production and so on. The analysis of the articulatory constituents of the quality of vowels allowed phoneticians to suggest the criteria which are conceived to be of great importance in classificatory description. First to be concerned here are the following criteria termed:
1. stability of articulation;
2. tongue position;
3. lip position;
4. character of the vowel end;
5. length;
6. tenseness. Stability of articulation specifies the actual position of the articulating organ in the process of the articulation of a vowel. There are two possible varieties:
a) the tongue position is stable;
b) it changes, that is the tongue moves from one position to another.
In the first case the articulated vowel is relatively pure, in the second case a vowel consists of two clearly perceptible elements. There exists in addition a third variety, an intermediate case, when the change in the tongue position is fairly weak. So according to this principle the English vowels are subdivided into:
1. monophthongs,
2. diphthongs,
3. diphthongoids.
This interpretation is not shared by British phoneticians. A.C. Gimson, for example, distinguishes twenty vocalic phonemes which are made of vowels and vowel glides. Seven of them are treated as short phonemes: [i], [e], [æ], [ɒ], [u], [٨], [ə] and thirteen as long ones: [a:], [ɔ:], [з:], [i:], [u:], [ei], [зu], [ai], [au], [ɒu], [iə], [εə], [uə] five of which are considered relatively pure: [a:], [ɔ:] [з:], [i:], [u:]; the rest are referred to long phonemes with different glides: [ei], [ai], [ɒ I] with a glide to [i]; [зu], [au] with a glide to [u]; and [iə], [εə], [uə] with a glide to [ə]. Diphthongs are complex entities just like affricates, so essentially similar complications are known to exist with them. The question is whether they are monophonemic or biphonemic units.
Scholars like V.A. Vasilyev and L.R. Zinger grant the English diphthongs monophonemic status on the basis of articulatory, morphonological and syllabic indivisibility as well as the criteria of duration and commutability. As to articulatory indivisibility of the diphthongs it could be proved by the fact that neither morpheme nor syllable boundary that separate the nucleus and the glide can pass within it, for example: [′sei-iŋ] saying, [′krai-iŋ] crying, [in-′ʤɔ-iŋ] enjoying, [′slзu-ə] slower, [′plзu-iŋ] ploughing, [′kliə-rə] clearer, [′εə-riŋ] airing, [′рuə-rə] poorer. The present study of the duration of diphthongs shows that the length of diphthongs is the same as that that characterizes the English long monophthongs in the same phonetic context, cf. [sait – si:t], [кзut – kɔ:t]. Finally the application of commutation test proves the monophonemic status of diphthongs because any diphthong could be commutated with practically any vowel. It could be exemplified in the following oppositions: [bait — bit] bite – bit [bait—b٨t] bite – but [bait — bɔ:t] bite – bought and so on.
Monophonemic character of English diphthongs is proved by native speakers’ intuition, who perceive these sound complexes as a single segment. Another principle we should consider from phonological point of view is the position of the tongue. For the sake of convenience the position of the tongue in the mouth cavity is characterized from two aspects, that is the horizontal and vertical movement. According to the horizontal movement phoneticians distinguish five classes of English vowels. They are:
1. front: [i:], [e], [ei], [æ], [ε(ə)];
2. front-retracted: [I], [I(ə)];
3. central: [٨] [з:] [ə], [з(u)], [ε(ə)];
4. back [ɒ], [ɔ:], [u:], [a:];
5. back-advanced: [u], [u(ə)].
British phoneticians do not single out the classes of front-retracted and backadvanced vowels. So both [i:] and [i] vowels are classed as front, and both [u:] and [u] vowels are classed as back. As to the tongue position in its vertical movement British scholars distinguish three classes of vowels: high (or close), mid (or half-open), and low (or open) vowels. Thus the following six groups of vowels are distinguished: 1. close a) narrow: [i:] [u:]; b) broad: [i], [u], [i(ə)], [u(ə)]; 2. mid a) narrow: [e], [з:], [ə], [e(i)], [з(u)]; b) broad: [ə], [٨]; 3. open a) narrow: [ε(ə)], [ɔ:], [ɒ (i)]; b) broad: [æ], [a(i, u)], [ɒ], [a:] Another feature of English vowels which is sometimes included into the principles of classification is lip rounding. Traditionally three lip positions are distinguished, that is spread, neutral and rounded. For the purpose of classification it is sufficient to distinguish between two lip positions: rounded and unrounded, or neutral. The fact is that any back vowel in English is produced with rounded lips, the degree of rounding is different and depends on the height of the raised part of the tongue; the higher it is raised the more rounded the lips are. So lip rounding is a phoneme constitutive indispensable feature, because no back vowel can exist without it. Another property of English vowel sounds – checkness depends on the character of the articulatory transition from a vowel to a consonant. This kind of transition (VC) is very close in English unlike Ukrainian. As a result all English short vowels are checked when stressed. The degree of checkness may vary and depends on the following consonant. Before fortis voiceless consonant it is more perceptible than before a lenis voiced consonant or sonorant.
All long vowels are free. The English monophthongs are traditionally divided into two varieties according to their length: a) short vowels: [i], [e], [æ], [ɒ], [u], [٨], [ə]; b) long vowels: [i:], [a:], [ɔ:], [з:], [u:]. A vowel like any sound has physical duration – time which is required for its production (articulation). When sounds are used in connected speech they cannot help being influenced by one another. Duration is one of the characteristics of a vowel which is modified by and depends on the following factors:
1. its own length,
2. the accent of the syllable in which it occurs,
3. phonetic context,
4. the position of the sound in a syllable,
5. the position in a rhythmic structure,
6. the position in a tone group,
7. the position in a phrase,
8. the position in an utterance,
9. the tempo of the whole utterance,
10. the type of pronunciation,
11. the style of pronunciation.
The problem the analysts are concerned with is whether variations in quantity or length are meaningful (relevant), that is whether vowel length can be treated as a relevant feature of English vowel system. Different scholars attach varying significance to vowel quantity. The approach of D. Jones, an outstanding British phonetician, extends the principle, underlying phonological relevance of vowel quantity. That means that words in such pairs as [bid] – [bi:d], [sit] – [si:t], [ful] – [fu:d], [′fɒ:wə:d] (foreword) – [′fɔ:wəd] (forward) are distinguished from one another by the opposition of different length, which D. Jones calls chronemes. The difference in quantity is considered to be decisive and the difference in quality (the position of the active organ of speech) is considered to be subordinate to the difference in quantity. According to the point of view of V.A. Vassilyev, English is not a language in which chronemes as separate prosodic phonological units can exist. One more articulatory characteristic needs our attention. That is tenseness. It characterizes the state of the organs of speech at the moment of production of a vowel. Special instrumental analysis shows that historically long vowels are tense while historically short vowels are lax. Summarizing we could say that phonological analysis of articulatory features of English vowels allows to consider functionally relevant the following two characteristics: a) stability of articulation, b) tongue position. The rest of the features mentioned above, that is lip position, character of vowel end, length, and tenseness are indispensable constituents of vowel quality. Though they have no phonological value they are considerably important in teaching English phonetics.It is well-known that a vowel in an unstressed syllable is perceived as very short, weak, and indistinct.
The unstressed syllables are usually associated with vowels of central or centralized quality [ə], [i], sometimes [u] and the diphthongs [зu], [ai] (or a syllabic consonant), e.g. among [ə’m٨ŋ], before [bi’fɔ:], useful [‘ju:sful], tomato [tə’ma:tзu], exercise [‘eksəsaiz], sudden [‘s٨dn]. Also vowels of full quality sometimes occur in unstressed positions, often in borrowed words of Latin and Greek origin, e.g. architect [‘a:kutekt], paragraph [‘pærəgra:f], canteen [kaen’ti:n]. These nonreduced vowels in unstressed syllables are typical of all styles of pronunciation. Then again partially reduced sounds are found in unstressed positions. They appear in more formal and careful style of pronunciation instead of the neutral sound used in informal casual speech. Cf.: phonetics [fзu’netiks – fз’netiks – fə’netiks]. Our next point should be made in