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example, idiolectal variation is observed when the speaker stammers, mumbles or
lisps.
Diaphonic
variation is caused by historical tendencies active in certain localities
and is seen, for example, in the speech of dialectal speakers. People speaking with a
foreign accent also demonstrate diaphonic variation, as a rule.
The less noticeable variation is
allophonic
. It is conditioned by phonetic
environment, for example the phoneme [æ] depending on the word and its place in
the utterance may be pronounced as [ə], or sound [r] word finally may be pronounced
differently that when it is positioned word-initially or word-medially.
UNIT 3. ENGLISH CONSONANTS
§ 1. Consonants as the sounds articulated with obstruction
In all languages speech sounds are traditionally divided into two main groups:
vowels and consonants; some languages are known to have semivowels too.
If looked upon from the auditory viewpoint, consonants are sounds that have
voice and noise combined, while vowels are sounds consisting of voice only.
From the articulatory point of view, the difference between them is stipulated by
the work of speech organs. When vowels are produced, their articulation meets no
obstruction. In case with consonants, various obstructions are made (teeth, lips, etc.).
Thus, the following definitions can be applied to vowels and consonants:
Достарыңызбен бөлісу: 
