Modifications of Vowels in Connected Speech

Date: 2015-10-07; view: 7838.

Vowels

Talking about vowels requires first to specify their articulatory and acoustic characteristics. As was mentioned earlier, vowels unlike consonants are produced with no obstruction to the stream of air, so on the perception level their integral characteris­tic is naturally tone, not noise.

It would be interesting to know that a minimum vowel sys­tem of a language is likely to take the form of

The most important characteristic of the quality of these vowels is that they are acoustically stable. They are known to be entirely different from one another both articulatorily and acoustically. Consequently they may well be said to form boundaries of "phonetic field of vowels" in a modern man's life. Thus they display the highest degree of unlikeness and so maxi­mum of abilities of people as regards to vowels. We could add that the commonest vowel system adds two other vowels to this minimum triangle to give a five vowels system of the type:

In the matter of the English language it would be fair to men­tion that due to various reasons it has developed a vocalic sys­tem of a much larger number of phonemes.

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. From what we have said it follows that isolation and distinctions of the above-mentioned articulatory features are done only for the sake of analysis with the purpose of describing the vocalic system of the English language.

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:

a) stability of articulation;

b) tongue position;

c) lip position;

d) character of the vowel end;

e) length;

f) tenseness.

In the part that follows, each of the above-mentioned princi­ples will be considered from phonological point of view.

Stability of articulationspecifies 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 an­

other. 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:

a) monophthongs,

b) diphthongs,

c) diphthongoids.

Though the interpretation we have just given is an obvious matter for Soviet phoneticians it does not mean that this way of seeing the situation is shared by British phoneticians. A.C. Gimson, for example, distinguishes twenty vocalic phonemes which are made of vowels and vowel glides (57). Seven of them are treated as short phonemes: [ı], [e], [æ], [ɒ], [u], [ʌ], [ə] and thir­teen as long ones: [a:], [ɔ:], [ɜ:] [i:], [u:], [eı], [so], [aı], [au], [ɒu], [ıə], [ɛə], [uə] five of which are considered relatively pure: [a:], [ɔ:] [ɜ:], [i:], [u:]; the rest are referred to long phonemes with dif­ferent glides: [eı], [aı], [ɒı] vith a glide to [ı], [ɜu], [au] with a glide to [u]; and [iə], [ɛə], [uə] with a glide to [ə]. It is easy to see that this way of presenting the system does not reveal the actual difference between long monophthongs and long diphthongoids and consequently we could say that it fails to account adequate­ly for more delicate distinctions. Here we have to admit that though it is not a decisive difference this is the case when expli­cit information about distinguishing between different degrees of instability is practically useful far teaching purpose. For the learner of English it is important to know that the vowels [i:] and [u:] are diphthongized in modern English and the tendency for diphthongization is becoming gradually stronger.

At this point we are ready to consider the question of the phonemic status of English diphthongs. Diphthongs are complex entities just like affricates described in the previous section, so essentially similar complications are known to exist with them. The question is whether they are monophonemic or biphonemic units. It is not the lack of evidence that does not enable to an­swer it. We might say that now there is much available data ob­tained with the help of the computer equipment. Though the problem has been given a lot of attention up to now it has been neither completely discounted nor satisfactorily explained. The reason that accounts for the present situation could be formu­

lated in the following way: it is impossible to find a simple and logic criterion which might serve as a basis for a decision.

Soviet scholars 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: ['seı-ıŋ] saying, ['kraı-ıŋ] crying, [in-'ʤɔı-ıŋ] enjoying, ['slɜu-ə] slower, ['plɜu-ıŋ] ploughing, ['klıə-rə] clearer, ['ɛə-rıŋ] airing, [puə-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. [saıt — set], [kɜut — 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 —bʌt] bite —but

[bait —[ʧ] 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.

The above-mentioned considerations make Soviet linguists V. A. Vassilyev (79), L. R. Zinder (16) treat English diphthongs as monophonemic entities.

The suggestion that English diphthongs are monophonemic is necessary not only for linguistic purpose; accepting that fin­ding is also of practical importance in teaching English as a foreign language, since in Russian there are no diphthongs or diphthongoids as phonemic entities. Such combinations of sounds as [йа, йо, йу], [ой, ай], [ау, уа] (яд, йод, юг, рой, край, мяукать, вуаль), and others are biphonemic clusters, consisting either of a vowel and the Russian sonorant [й] or two vowels. Both elements in the clusters are equally energetic and distinct. So special attention should be given to the pronunciation of En­glish diphthongs which consist of two elements, the first of which, the nucleus, being strong and distinct and the second, the glide, being very weak and indistinct.

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 Soviet phoneticians distinguish five classes of English vowels. They are:

1) front: [i:], [e], [eı], [æ], [ɛ(ə)];

2) front-retracted: [ı], [ı(ə)];

3) central: [ʌ] [ɜ:] [ə], [ɜ(u)], [ɛ(u)];

4) back [ɒ], [ɔ:], [u], [a:];

5) back-advanced: [u], [u(ə)].

A slightly different approach seems to have been taken by British phoneticians. They do not single out the classes of front-retracted and back-advanced vowels. So both [i:] and [ı] vowels are classed as front, and both [u:] and [u] vowels are classed as back. The latter point of view does not seem to be consistent enough. The point is that the vowels in these two pairs differ in quality which is partially due to the raised part of the tongue. So in this case a more detailed classification seems to be a more pre­cise one since it adequately reflects the articulatory distinction actually present in the language.

The other articulatory characteristic of vowels as to the tongue position is its vertical movement. The way British and Soviet phoneticians approach this aspect is also slightly different. British scholars distinguish three classes of vowels: high (or close), mid (or half-open), and low (or open) vowels. Soviet pho­neticians made the classification more detailed distinguishing two subclasses in each class, i.e. broad and narrow variations of the three vertical positions of the tongue. Thus the following six groups of vowels are distinguished:

1) close a) narrow: [i:] [u:];

b) broad: [ı], [u], [ı(ə)], [u(ə)];

2) mid a) narrow: [e], [a:], [ə], [e(ı)]_t [ɜ(u)];

b) broad: [ə], [ʌ];

3) open a) narrow: [ɛ(ə)], [ɔ:], [ɔ(ı)];

b) broad: [æ], [a(ı, u)], [ɒ], [a:]

The phonological relevance of the criterion under discussion can be easily discovered in the folloving oppositions:

[pen — pæn] pen — pan [kæp — ka:p] cap — carp

[pen — pin] pen — pin [kæp — cʌp] cap — cup

[bin — bi:n] bin — been [bʌn — ba:n] bun — barn

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. In English lip rounding is not relevant phonologically since no two words can be differentiated on its basis. Lip rounding takes place rather due to physiological reasons than to any other. 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.

Our next point should be made about another property of English vowel sounds that is traditionally termed checkness. This quality 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 Russian. 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.

It may be well to mention that though this characteristic has no phonological value it is of primary importance for Russian learners of English. It should be remembered that since all Rus­sian vowels are free special attention should be drawn to making English short vowels checked. It is not the length of vowels that should be the point of attention but the character of the transi­tion of a vowel into a consonant. Such words as body, seven, bet­ter, matter should be divided into syllables in such a way that the vowels should remain checked unlike Russian Боря, Сева, бита, мята.

At this point we are ready to consider another articulatory characteristic of English vowels, that is their length or quantity.

The English monophthongs are traditionally divided into two varieties according to their length:

a) short vowels: [ı], [e], [æ], [ɒ], [u], [ʌ], [ə];

b) long vowels: [ı:], [a:], [ɔ:], [з:], [u:].

We should point out that vowel length or quantityhas for a long time been the point of disagreement among phoneticians.

It is common knowledge that 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 (64). That means that words in such pairs as [bid] — [bi:d], [sıt] — [si:t], [ful] — [fu:l], ['fɔ:wз: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 the outstanding Soviet phonetician V. A. Vassilyev, English is not a language in which chronemes as separate prosodic phonological units can exist (79, p. 204).

If a phonetician wants to approach this aspect from phono­logical point of view he should base his theoretical conclusion on the two laws characterizing any system:

1. A relevant feature must characterize a number of units. Let us take a sample of palatalization in Russian. Compare: ел — ель, рад — ряд, нов — новь and so on. These oppositions form a correlation system. Any correlation should have a number of op­positions. A sign of correlation (palatalization in the above-men­tioned example) is a distinctive feature of a number of pho­nemes. The analysis of English vowels shows that they can hardly form quantitative correlation. For the sake of economy the following correlation is often brought about.

Let us analyze each of these pairs.

In actual speech the sounds [i:] and [u:] are normally realized in RP as diphthongized vowels. So [ı] and [u] are opposed to diphthongoids but not to long monophthongs.

The opposition [з:] — [ə] is a fairly specific one because the [ə] phoneme never occurs in a stressed syllable and forms the core of unstressed vocalism in English. The phoneme [з:] seldom occurs in an unstressed syllable.

The opposition [a:] — [ʌ] is arbitrary. As a result there is only one pair of opposed phonemes remaining, e.g. [ɔ:] — [ɒ]. That means that quantitative correlation exists only in one opposi­tion, so on this ground it cannot be treated as a phonologically relevant feature.

2. A feature can be systemic if it does not depend on the con­text. As to the absolute length of English historically long and historically short vowels it varies and depends on a lot of factors, the first being phonetic context. A. C. Gimson, for example, points out that [i:] in beat is only half about as long as the [i:] of bee and may approximately have the same duration as the [ı] vowel of bid because it is generally known that a voiced conso­nant following a vowel increases its length (57). But still the words bid and bead are perceived as different words because the vowels are different in quality, [ı] being front retracted, a pure monophthong, and [i:] being front close (narrow) and a diph­thongized vowel. The conclusion that follows is that vowel quantity cannot be considered a minimal distinctive feature since it varies under the influence of different phonetic context. So it is an incidental feature that characterizes sounds of a certain quali­ty. It is worth noting here that an element accompanying anoth­er element cannot be a sign itself and therefore cannot be classed as part of a system. This is one of the basic laws of any system. Summarizing we may say that this is the approach to quantity

of English vowels from phonological point of view. It is share by all Soviet specialists in English phonetics as well as by most modern British phoneticians.

It may be well to mention that the [æ] vowel being classed historically short tends to be lengthened in Modern English, especially before lenis consonants [b], [d], [g], [ʤ], [m], [n], [z]. In this^: position [æ] has the same quantity as long vowels [i:], [a:], [ɔ:]J [u:], [з:]. This extra length, as A. C. Gimson points out, serves as additional distinctive feature and the qualitative — quantitative relation of [æ] — [e] tends to become of the same type as [i:] — [i] (57). From this point of view [æ] can possibly belong to the sub class of long vowels, and consequently the twelve English Iong vowel phonemes may be divided into six phonemic pairs which| members differ both in quality and in quantity, and of the two factors it is likely that the quality carries the greater contrastive weight.

There is one more articulatory characteristic that 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. This characteristic is of extraphonological type so tenseness may be considered as indispensable concomitant feature of English long vowels. On this ground it may be included into classificatory description of vowels because it might be helpful in teaching the students of English since there are no tense vowels in Russian.

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.

So far we have given a lot of attention to the problems of classifying English vowels. Vowels as items of vocalic system were analyzed as if pronounced in a stressed position in a word. At this point we should discuss various properties displayed by vowels in unstressed positions and considerthem from articula­

tory and phonological point of view. 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], [ı], sometimes [u] and the diphthongs [зu], [aı] (or a syllabic consonant), e.g. among [ə'mʌŋ], before [bı'fɔ:], useful ['ju:sful], tomato [tə'ma:tзu], exercise ['eksəsaız], sudden ['sʌdn].

Also vowels of full quality sometimes occur in unstressed po­sitions, often in borrowed words of Latin and Greek origin, e.g. architect ['a:kıtekt], paragraph ['pærəgra:f], canteen [kæn'ti:n].

These nonreduced vowels in unstressed syllables are typical of all styles of pronunciation.

It is important to mention here that in the Russian language a vowel never preserves its full quality in unstressed position, it is usually reduced. So the English vowels of full quality in unstressed syllables require the teachers' special attention. Cf.: transport ('trænspɔ:t] — транспорт ['транспърт].

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'netıks — fз'netıks — fə'netıks].

Our next point should be made in connection with the phone­mic status of the neutral sound [ə]. The phonological analysis marks the opposition of the neutral sound to other unstressed vowels, the most common among them being [1]. In the minimal pairs: officers ['ɒfısəz] — offices [ɒfısız]; accept [ək'sept] — except [ık'sept], armour ['a:mə] — army ['amı] the neutral sound is phonologically opposed to the phoneme [ı] with its own distinctive fea­tures capable of differentiating the meaning of lexical units. So the neutral sound [ə] in officers, accept, armour is an independent pho­neme opposed to the [1] phoneme of the minimal pairs given above.

On the other hand, the problem of the phonemic status of the neutral sound has a morphological aspect. In English as well as in Russian there are numerous alternations of vowels in stressed and unstressed syllables between the derivatives of the same root or different grammatical forms of the same word. Cf.:

[æ] — [ə] man — sportsman

[ʌ] — [ə] some — wholesome

[ɒ] — [ə] combine n — combine v

[eı] — [ə] operation — operative

[зu] — [ə] post — postpone

The alternated sounds are allophones of one and the same phoneme as they are derivatives of the same lexical units, the same morphemes. Thus the neutral sounds in the examples above are the neutralized allophones of the nonreduced vowels of full formation; so [ə] in sportsman is an allophone of the [æ] phoneme as in man; [ə] in photography is an allophone of the [зu] phoneme as in photograph.

We might conclude by saying that we have tried to look at the consonantal and vocalic systems of the English language from phonological point of view. Applying this sort of analysis enables us to define what properties displayed by English sounds are significant in making them items of a system. It is worth saying that phonologically relevant articulatory features should attract direct attention of a would-be teacher of English because they form the basis of the pronunciation system of the language. Non-relevant but indispensable features should also be acquired being both phonetically correct and necessary for teaching pur­poses. If we want to speak a foreign language in an objectively correct way it is natural we should pay attention to the quality of our sounds which is constituted by articulatory features of both kinds.

In discussing vowels we should now turn to vowel reduction as it is one of the factors that condition the defining of the pho­nemic status of vowel sounds in a stretch of speech. The modifi­cations of vowels in a speech chain are traced in the following directions: they are either quantitative or qualitative or both. These changes of vowels in a speech continuum are determined by a number of factors such as the position of the vowel in the word, accentual structure, tempo of speech, rhythm, etc.

The decrease of the vowel quantity or in other words the shortening of the vowel length is known as a quantitative modi­fication of vowels, which may be illustrated as follows:

1. The shortening of the vowel length occurs in unstressed positions, e. g. blackboard [ɔ:], sorrow [зu] (reduction). In these cases reduction affects both the length of the unstressed vowels and their quality.

Form words often demonstrate quantitative reduction in un­stressed positions, e.g.

Is -»he or ˎshe to blame? — [hi:] But:

At last he has ˎcome. — [hi]

-»2. The length of a vowel depends on its position in a word. It varies in different phonetic environments. English vowels are said to have positional length, as you probably remember from your practical course of phonetics, e.g. knee — need — neat (ac­commodation). The vowel [i:] is the longest in the final position, it is obviously shorter before the lenis voiced consonant [d], and it is the shortest before the fortis voiceless consonant [t].

Qualitative modification of most vowels occurs in unstressed positions. Unstressed vowels lose their "colour", their quality, which is illustrated by the examples below:

1. In unstressed syllables vowels of full value are usually sub­jected to qualitative changes, e.g. man [mæn] — sportsman ['spɔ:tsmən], conduct ['kɒndəkt] —conduct [kən'dʌkt]. In such cases the quality of the vowel is reduced to the neutral sound [ə].

These examples illustrate the neutralized (reduced) allo­phones of the same phonemes as the same morphemes are op­posed.

The neutral sound [ə] is the most frequent sound of English. In continuous text it represents about eleven per cent of all sounds. And if we add the occurrence of [ı] which is closely re­lated to [ə] in unstressed positions we get a figure close to twen­ty per cent — nearly one sound in five is either [ə] or the un­stressed [ı]. This high frequency of [ə] is the result of the rhyth­mic pattern: if unstressed syllables are given only a short dura­tion, the vowel in them which might be otherwise full is re­duced. It is common knowledge that English rhythm prefers a pattern in which stressed syllables alternate with unstressed ones. The effect of this can be seen even in single words, where a shift of stress is often accompanied hy a change of vowel quali­ty; a full vowel becomes [ə], and [ə] becomes a full vowel. Com­pare: analyse ['ænəlaız] — analysis [ə'nælısıs]; in both words full vowels appear in the stressed positions, alternating with [ə] in unstressed position. It would be impossible to have [ə] in a stressed syllable, and almost as impossible to have a full vowel in every unstressed syllable.

We should point out that in Russian there is a well-deve­loped system of unstressed vowels. All the Russian vowels are regularly subjected to reduction, the vowels [o] and [и] more

often than others. The degree of sound weakening depends on the place of the unstressed vowel in relation to the stressed one. The farther the unstressed syllable is from the stressed one the weaker the vowel in the unstressed syllable is, e.g. молоко [мълʌко́].

2. Slight degree of nasalization marks vowels preceded or fol­lowed by the nasal consonants [n], [m], e.g. "never", "no", "then", "men" (accommodation).

The realization of reduction as well as assimilation and ac­commodation is connected with the style of speech. In rapid col­loquial speech reduction may result in vowel elision, the com­plete omission of the unstressed vowel, which is also known as zero reduction. Zero reduction is likely to occur in a sequence of unstressed syllables, e.g. history, factory, literature, territory. It often occurs in initial unstressed syllables preceding the stressed one, e,g. correct, believe, suppose, perhaps.

The example below illustrates a stage-by-stage reduction (including zero reduction) of a phrase. Has he done it?

[hæz hi-ˏdʌn it]

[həz hi ˏdʌn it]

[əz ı ˏdʌn it]

[z ı ˏdʌn it]

We would like to conclude that certain interrelation which we observe between the full form of a word and its reduced forms is conditioned by the tempo, rhythm and style of speech.