The complete articulation of a speech sound — a vowel or a consonant — when said by itself in isolation consists of three stages:
1. The on-glide stage during which the articulating organs move to the position necessary for the articulation of a sound.
2. The hold stage, during which the articulating organs are kept in the position for a certain period of time.
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3. The off-glide stage during which the articulating organs i«'turn to the position of rest.
For example, the on-glide of [tj, pronounced in isolation, is the contact formed by the tip of the tongue placed against the teeth ridge. During the hold stage the air is compressed behind the closure; during the explosion stage, the organs forming the instruction part rapidly and the compressed air escapes abruptly-
Such isolation of sounds from the flow of speech is, however, to a great degree simplification of real processes. Speech sounds
■ íå seldom said by themselves, they are used in combination
with other sounds in connected speech. In the process of speech
the articulatory organs are moving continuously and the sounds
mostly merge one into another. The type of accommodation of
speech organs to the transition from one articulation to another
in each language depends on its specific phonetic laws. Very
often the three stages of articulation are not preserved — the off-
qlide of the preceding sound serves as the on-glide of the follow
ing sound and these transitional stages between the holds tend
in living oral speech to reduction or complete disappearance.
I or example, when a plosive is immediately followed by another
;>losive or by [tfj or [èç), there is only one explosion for the two
i 'losives. The closure of the organs of speech for the second con-
onant is made before the release of the first one. As a result the plosion of the first consonant is completely inaudible. In the word locked, for instance, the third stage (explosion) of [k] merges into the first stage (closing stage) of [t]. The consonant [k] has the first and the second stages, while the consonant |t] has only the second and the third stages.
In connected speech the sounds are subjected, in general, to two main types of influence: the reciprocal influence of neighbouring sounds and the influence on sounds by larger speech units and their elements, first of all — by the stress. The first i iroup of processes is called the combinative changes, the
■econd group — the positional changes.
The majority of changes of sounds in connected speech are
■ ombinative. The sounds are modified by other sounds near to
i hem in the phonetic sequence. In this case they lose the clear
ness and some peculiarities of their articulation, gaining, on the
other hand, some new articulatory features. As a rule, it is the
third stage (off-glide) of the articulation of the preceding sound
and the first stage (on-glide) of the following sound that undergo modifications.
As a result of mutual interaction of speech sounds in connected speech there is a number of phonetic processes such as assimilation, accommodation, elision and others.
ASSIMILATION
Assimilation is a process of alteration of speech sounds as a result of which one of the sounds becomes fully or partially similar to the adjoining sound. The word "assimilation" is an example of this phenomenon. This Latin word is composed of the preposition "ad" — to, and the adjective "similis" alike, similar. ad-similatio — assimilatio: [ds>ss] ([d] under the influence of the following (s] was changed to (s]).
The nature of assimilation is determined by objective physical and physiological conditions. Assimilation exists in every language, but its laws and forms in each language depend on the historically formed articulatory tendencies, typical of every language, and specific phonetic structures.
Types of assimilation can be distinguished according to: (1) direction, (2) degree of completeness, (3) degree of stability.
Assimilation can affect the place of obstruction and the active organ of speech; the work of the vocal cords; the position of the lips; the position of the soft palate; the manner of the release of plosive consonants.
Direction of Assimilation.The influence of the neighbouring sounds in English can act in a progressive, regressive or reciprocal (double) direction.
When some articulatory features of the following sound are changed under the influence of the preceding sound, which remains unchanged, assimilation is called progressive. For example.
(1) The pronunciation of the plural suffix -s of nouns depends on the quality of the preceding consonant: it is pronounced as [zj after voiced consonants, eg pens [pcnz), calls [ko:lz] and as [s] after voiceless consonants, eg desks [desks], books [buks].
(2) Within the words sandwich, grandmother, etc under the influence of [n] the consonant (d] changed into [n] and then disappeared, eg sandwich ['saennwid3>'saenwid3].
When the following sound influences the articulation of the preceding one assimilation is called regressive. For example, within the word width and in the word combination in them, the alveolar [d] and [n] become dental, before the interdental (9] and (d].
This type of assimilation is common both in English and in Russian. Assimilation in Russian acts mainly in regressive direction, progressive assimilation being rather rare in this language, eg êàïëÿ, òðåâîãà. The sonorants [ë] and [p] are partly devoiced under the influence of the preceding voiceless [n] ar.d [ò].
Reciprocal or double assimilation means complex mutual influence of the adjacent sounds. For example, within the word tree [tri:] the sonorant [r] is partly devoiced under the influence of the voiceless {t] and the alveolar [t] become; post-alveolar before the post-alveolar [r].
Degreeof Completeness.According to its degree, assimilation can be complete and incomplete. Assimilation is called complete in the case the two adjoining sounds become alike or merge into one. It always takes place when the two sounds differ only in one articulatory feature. We find cases of complete assimilation within words, eg cupboard ['cApbad>'c/b3d]; and at the word junction in fluent speech, eg less shy ['les'Jai > 'le/Jai].
Complete assimilation is also found in Russia.!, eg îòäåëàòü, îòäàòü; ñæàòü, áåç ñèë, ãîëîñ æåíùèíû, áðàò äðóãà.
Assimilation is called incomplete when the likeness of the adjoining sounds is partial as the assimilated sound retains its major articulatory features. For example, the sonorants [w, 1, r] are partly devoiced when preceded by the voiceless fortis [p, t, k, s, f, 0] within words: sweet [swi:t], place [pjeis], try [trii].
Degree of Stability.Many assimilatory phenomena of older stages in the development of the language have become obligatory in modern English, they may, or may not be reflected in spelling. Such changes which have taken place over a period of time within words are called historical, eg orchard (ort + yard) — ['D.tj3d>'o:tf3d].
In modern language obligatory assimilations are special allo-phonic variants characteristic of the natives' speech. The use of
the wrong allophone, though a non-phonemic mistake, amounts to mispronunciation and may be one of the causes of a foreign accent making understanding difficult. For example, a dental allophone of the alveolar [t] should be used when it is followed by (inter)dental [9] or [d] as in eighth [citQ].
Besides there are alot of widely spread but non-obligatory cases of assimilation which can be traced mainly at wordboundaries, eg
ten minutes ['ten 'minrts>'tem'mmits] '
ten girls ['ten 'g3:lz>'terj'g3:lz).
Non-obligatory assimilations are characteristic of fluent or careless speech and should he avoided by public speakers (lecturers, teachers, etc).
Quality of Adjacent Sounds.According to the quality of the adjacent sounds there can be four special cases of contact assimilation: (1) influence of a consonant on the adjacent consonant, (2) influence of a vowel on the adjacent vowel, (3) influence of a consonant on the adjacent vowel, (4) influence of a vowel on the adjacent consonant. We shall consider only the first case here.