Types of Sound Modifications

V. MODIFICATIONS OF SOUNDS IN CONNECTED SPEECH

When a phoneme is articulated separately it displays all its characteristic features. But phonemes are seldom articulated in isolation. In speaking they are generally used in sentences consisting of a number of words, and, consequently, are pronounced in sequences of sounds, interrupted by pauses. When phonemes are pronounced in sequences, we observe the phenomenon of adaptation - speech organs adjust themselves to make a more convenient transition from one articulation to another. They display a certain “economy” of effort. Of course, this “economy” may vary in different languages, depending on the articulation basis and phonetic laws in every language. Sound modifications are observed not only across word boundaries, but also across morpheme and syllable boundaries, as well as within morphemes. Such changes in the articulation of sounds in speech are mostly quite regular and predictable and can be grouped in the following way: assimilation, accommodation, vowel reduction and elision.

The modification of a consonant by a neighbouring consonant in the speech chain is known as assimilation. The term accommodation is used to denote the modification of consonants under the influence of the neighbouring vowels and vice versa. One of the most wide-spread sound changes is vowel reduction, that is weakening (either qualitative or quantitative) of vowels in unstressed positions. Elision or complete loss of sounds, both vowels and consonants, is also often observed in English.

In the adaptation of articulations to each other one of the two principles is generally involved:

1) speech organs are prepared beforehand for the articulation of a sound that follows and the phoneme that comes first is affected by the one that comes after it, then this assimilation is called regressive (for example in right now [t] is affected by the following nasal [n] and is pronounced with the nasal plosion);

2) the activity of speech organs continues after the sound for which they are prepared has been articulated and the phoneme that comes first affects the one that follows it, in this case the assimilation is progressive (for example, the verb and noun suffix - s and is voiceless when it is preceded by a voiceless phoneme, and it is voiced when it is preceded by a voiced phoneme – [si:ts – si:dz]; [sets – selz]).

Assimilation can also be historical and “living” or functioning. Classical examples of historical assimilation can be found in the words borrowed from Norman-French: permission, measure, etc. Here we see the adaptation of the articulation of [s] and [z] to the articulation of the [j]-phoneme: [pəˈmɪʃ(ə)n], [ˈmeʒə].

It is important to distinguish between “ obligatory ” (or fixed) and “ non-obligatory ” assimilation. Obligatory assimilation occurs in the speech of all people who speak a certain language, no matter what style of speech is used. It has become fixed as part of the phonological structure and is included in the articulation basis, so it has to be mastered in learning the pronunciation of a certain language. Non-obligatory assimilation appears in rapid, casual speech and its degree may vary, depending on speaking rate, style and individual peculiarities of speech.

Depending on the degree to which articulations are adapted complete and partial assimilation is distinguished. When one or more features of the phoneme are affected, we have partial assimilation as in tree, for example, [t] becomes post-alveolar under the influence of the following [r], but it retains its distinctive features and is still constrictive, forelingual and fortis. When all the features of the phoneme are adapted, we have a case of complete assimilation, for example, in rapid casual speech [t] will become [p] before a bilabial consonant, as in that person: [ðæpˈpɜ:sn].

Such cases of assimilation create something of a problem for the phoneme theory, as it’s not clear whether one phoneme has been substituted for another phoneme or one of its allophones. Traditionally, if a phoneme loses one of its distinctive features it is said to be a different phoneme, phonemes are supposed not to overlap in their allophones. Nowadays some phoneticians don’t consider this restriction important any more and regard these sounds as allophones of one phoneme.

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