Theory of phonetics

The position of the tongue. It is characterized by from two aspects, that is the horizontal and vertical movement. According to the horizontal movement Soviet phoneticians* distinguish five classes of the English vowels. They are:

1. 
   front: [i:], [e], [eI], [x], [F(q)];
   
2. 
   *front retracted: [I], [I(q)];
   
3. 
   central: [A], [E:], [q], [E(V)], [F(V)];
   
4. 
   back: [P], [L], [u:], [R];
   
5. 
   *back-advanced: [V], [V(q)].
   

According to the vertical movement

British scholars distinguish three classes of vowels:	Soviet phoneticians made the classification more detailed distinguishing two subclasses in each class:
high (or close); mid (or half-open); 3) low (or open)	1) broad; 2) narrow variation

Thus the following six groups of vowels are distinguished:

1) close a) narrow variation: [i:], [u:];
b) broad: [I], [V], [I(q)], [V(q)].
2) mid a) narrow variation: [e], [E:], [q], [e(I)], [E(V)];
b) broad: [q], [A];
3) open a) narrow variation: [F(q)], [L], [OI];
b) broad: [x], [a(I, V)], [P], [R]
Lip rounding. Traditionally three lip positions are distinguished:

1. 
   spread;
   
2. 
   neutral;
   
3. 
   rounded.
   

Lip rounding takes place rather due to physiological reasons than to any other. Any back vowel in English is produced with rounded lips, the degree of rounding is different and depends on the height of the raised part of the tongue; the higher it is raised the more rounded the lips are. So lip rounding is a phoneme constitutive indispensable feature, because no back vowel can exist without it.
Checkness. The typical English transition is from a vowel to a consonant (VC). As a result all short English vowels are checked when unstressed. The degree of checkness may vary and depends on the following consonant. Before a fortis voiceless consonant it is more perceptible than before a lenis voiced consonant. All long vowels are free.
For example, doggy, level, setter, fatter are divided into syllables in such a way that the short vowels remain checked; unlike Russian Боря, Сева, Рита, тряпка.
The English monophthongs are traditionally divided into two varieties according to their length:

1. 
   short vowels: [I], [e], [x], [P], [V], [A], [q];
   
2. 
   long vowels: [i:], [R], [L], [E:], [u:].