STABILITY OF ARTICULATION
All English vowels are divided into three groups: pure vowels or monophthongs, diphthongs and diphthongoids.
Monophthongs are vowels the articulation of which is almost unchanging. The quality of such vowels is relatively pure. The English monophthongs are: [ı], [e], [æ], [L], [a:], [Ŋ], [Ɔ:], [ʊ], [з:], [ә].
In the pronunciation of diphthongs the organs of speech glide from one vowel position to another within one syllable. The starting point, the nucleus, is strong and distinct. The glide which shows the direction of the quality change is very weak. The English diphthongs are: [eı], [aı], [Ɔı], [aʊ], [əʊ], [eə], [ɪə], [ʊə].
In the pronunciation of diphthongoids the articulation is slightly changing but the difference between the starting point and the end is not so distinct as it is in the case of diphthongs. There are two diphthongoids in English: [i:], [u:].
tongue position
The tongue may move forward and backward, up and down, thus changing the quality of vowel sounds.
(1) When the tongue moves forward and backward, various parts of it may be raised in the direction of the palate.
· When the tongue is in the front part of the mouth, and the front part of it is raised to the hard palate, a f r o n t vowel is pronounced: [i:], [e], [æ].
· When the tongue is in the front part of the mouth, but slightly retracted, and the part of the tongue nearer to centre than to front is raised, a f r o n t–r e t r a c t e d vowel is pronounced: [ı].
· When the front of the tongue is raised towards the back part of the hard palate, the vowel is called c e n t r a l: [L], [з:], [ә].
· When the tongue is in the back part of the mouth, and the back of it is raised towards the soft palate, a b a c k vowel is pronounced: [a:], [Ŋ], [Ɔ:], [u:].
· When the tongue is in the back part of the mouth, but is slightly advanced, and the central part of it is raised towards the front part of the soft palate, a b a c k–a d v a n c e d vowel is pronounced: [ʊ].
(2) Moving up and down in the mouth various parts of the tongue may be raised to different height towards the roof of the mouth.
· When the front or the back of the tongue is raised high towards the palate, the vowel is called c l o s e: [i:], [ı], [ʊ], [u:].
· When the front or the back of the tongue is as low as possible in the mouth, o p e n vowels are pronounced: [æ], [a:], [Ŋ], [Ɔ:].
· When the highest part of the tongue occupies the position intermediate between the close and the open one, m i d vowels are pronounced: [e], [L], [з:], [ә].
It is necessary to distinguish broad and narrow variants of close, mid and open vowels:
C l o s e vowels | narrow variant | [i:], [u:] |
broad variant | [ı], [ʊ] | |
M i d vowels | narrow variant | [e], [з:], [ә(ʊ)] |
broad variant | [L], [ә], [e(ә)] | |
O p e n vowels | narrow variant | [Ɔ:], [Ɔ(ı)] |
broad variant | [æ], [a:], [Ŋ], [a(ı, ʊ)] |