IV. The functional aspect of speech sounds
Key words: allophone, allophonic (narrow) / phonemic (broad) transcription, commutation test, complementary / contrastive/parallel distribution, distinctive (relative) / non–distinctive (irrelevant, redundant) features, free variations, formally distributional method, invariant, minimal pairs, morphonology, neutralization, phone, phoneme, phonetic / phonological mistakes, a principal / subsidiary (secondary) allophone, semantically distributional method, set of oppositions, sound.
4.1 Phoneme and Allophones
Phoneticians not only describe and classify the material form of phonetic units. They are also interested in the way in which sound phenomena function in a particular language and what part they play in communication. The branch of phonetics that studies the linguistic function of consonant and vowel sounds, syllabic structures, word accent and prosodic features is called phonology. Unlike phonetics itself, whose domain is articulatory and acoustic features, phonology investigates the social aspect of sounds, syllables, phrases and so on.
Let’s first look at the linguistic function of individual sounds. When we speak we produce a continuous stream of sounds. In studying speech we divide this stream into small segments, but how do we decide how to divide it and how many different sounds there are in English? As we see the term “sound” can be interpreted in two rather different ways. In the first place, we can say that [t] and [d] are two different sounds in English. They contrast with each other and differentiate the meaning of words. Take, for example, [tu: - du:], [tɪk - dɪk], etc. But on the other hand, if we listen carefully to the [t] in “take” and compare it with the [t] in “at the”, we can hear that the two sounds are also not the same, the [t] of “take” is alveolar, while the [t] of “at the” is dental. In both examples the sounds differ in one articulatory feature only (t/d - voiceless/voiced; t/tð - alveolar/dental). But in the second case the difference between the sounds doesn’t change the meaning of the words. It is perfectly clear, that the sense of the word “sound” in these two cases is different. To avoid this ambiguity, linguists use two separate terms: “phoneme” is used to mean “sound” in its contrastive sense, and “allophone” is used for sounds which are variants of a phoneme: they usually occur in different positions in the word, cannot contrast with each other, so they are not used to differentiate the meaning.
The Phoneme Theory came into being in Russia. Its originator was Prof. Baudouin de Courteney, the founder of the Kazan Linguistic School. There are a great number of views on the Phoneme Theory, but we shall not go deep into detail and so we’ll speak about the view, which is accepted in our University and which seems to embrace all the aspects of the phoneme and thus is the most suitable for the purpose of teaching.
The linguists have not yet created the definition of the phoneme acceptable to all. There are several conceptions of the phoneme. One of them was suggested by L. V. Scherba, who seemed to reflect all the aspects and functions of the phoneme. He described it as a functional, material and abstract unit. Another phonetician, V. A. Vassilyev, developed this concept and defined the phoneme like this: "The segmental phoneme is the smallest (i.e. further indivisible into smaller consecutive segments) language unit (sound type) 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" [V. A. Vassilyev, p. 136].
Let us consider the phoneme from the point of view of its three aspects. Firstly, the phoneme is a functional unit. It means that the opposition of phonemes in the same phonetic environment differentiates the meaning of words, grammatical forms and even the whole phrases: [slɜʊ - blɜʊ], [tu:θ - ti:θ] (slow - blow; tooth - teeth); [hi: wəz ˈhɜ:d ˎbædlɪ - hi: wəz ˈhɜ:t ˎbædlɪ] (He was heard badly - He was hurt badly). Phonemes are in parallel distribution; they appear in the same phonetic context and form a semantic contrast.
Secondly, the phoneme is material, real and objective. That means that it is realised in speech in the form of speech sounds, its allophones (or actually pronounced speech sounds).
Allophones of the same phoneme must meet the following requirements:
- though they possess similar features, they frequently show considerable phonetic difference;
- they never occur in the same phonetic context, so they can’t be opposed to each other and can’t differentiate the meaning. In this case allophones are said to be in complementary distribution.
Those allophones which do not undergo any significant changes in the chain of speech (for example, when they occur in an isolated position) are called principal. At the same time there are predictable changes, which sounds undergo in different phonetic context (especially under the influence of the neighbouring sounds, intonation, etc.). Such allophones are called subsidiary or secondary.
The examples below illustrate the articulatory modifications of the phoneme [t] in various phonetic contexts:
[t] in "tea" is a bit palatalized; in "not there" it is dental; in "not quite" it loses its plosion; in "little" it is pronounced with the lateral plosion; in "not many" - with the nasal plosion; in "try" it becomes post-alveolar; in "stare" - non-aspirated. In spite of the differences in the pronunciation of [t] in different positions it can be easily noticed that all its allophones possess some common features, all of them are forelingual, fortis stops.
It goes without saying that in teaching English pronunciation the difference between the allophones of the same phoneme should be considered. The starting point is, of course, the articulation of the principal allophone, but special training of the subsidiary allophones should be provided too.
But in fact, no speech sounds are absolutely alike. Apart from predictable changes there are stylistic, dialectal, individual, occasional modifications. In fact, we pronounce phones. Most of social information (the locality he/she lives in, age, sex, occupation, emotional state, etc.) about the speaker comes not from phonemic distinctions, but from phonetic ones.
Not let's consider the third aspect of the phoneme. As we have already said it is an abstract linguistic unit. Native speakers may not realise the difference between allophones, though they are quite aware of the phonemes of their language. It happens because this difference doesn’t affect the meaning. Sounds which have similar functions in the language (in other words they cannot differentiate the meaning) tend to be considered the "same" by the community using that language, while those which have different functions tend to be classed as "different". So native speakers abstract themselves from the difference between the allophones of the same phoneme because it has no functional value. At the same time they understand that they can’t change any of the articulatory features which are common to all the allophones of the same phoneme without destroying the meaning. This functionally relevant bundle of articulatory features is called the invariant of the phoneme. Neither of the articulatory features that form the invariant of the phoneme can be changed without affecting the meaning.
For example, the invariant of [t] consists of the following articulatory features: occlusive, forelingual and fortis. How can we prove it? If we change the occlusive articulation for constrictive, [t] will be replaced by [s] (tea-sea; tick-sick); if we change the forelingual articulation for backlingual [t] will be replaced by [k] (bat-back; tick-kick); if the fortis articulation is changed for lenis [t] will be replaced by [d] (bet-bed; tear-bear). That is why it is possible to state that occlusive, forelingual and fortis characteristics of the phoneme [t] are generalized in the mind of the speaker into the invariant of this phoneme.
The articulatory features which form the invariant of the phoneme are called distinctive or relevant. The articulatory features which do not serve to distinguish the meaning are called non-distinctive or irrelevant. The distribution of distinctive and non-distinctive features is language specific; it is different in different languages. For example, aspiration is a non-distinctive feature in the English language, but in Hindi or Korean it is relevant as aspirated and non-aspirated sounds may appear in the same phonetic context and contrast the meaning of words.
As it has been mentioned above any change in the invariant of the phoneme affects the meaning. Naturally, anyone who studies a foreign language makes mistakes in the articulation of some sounds. L.V. Scherba classifies the pronunciation mistakes as phonological and phonetic.
If any allophone of some phoneme is replaced by an allophone of a different phoneme, the mistake is called phonological, because the meaning of the word is affected. For example: [det – ded], [bi:t - bɪt], [bed - bæd] (debt-dead; beat-bit, bed-bad).
If an allophone of the phoneme is replaced by another allophone of the same phoneme the mistake is called phonetic. The meaning of the word does not change. Nevertheless, language learners are advised not to let phonetic mistakes into their pronunciation, as they cause their foreign accent.