Based pronunciation standards of English

6)Articulatory and physiological classification of English vowels in the works of Soviet, British and American phoneticians.
The first linguist who tried to classify vowel sounds for all languages was D.Jones. He devised the system of 8 cardinal vowels. The basis of the system is physiological.
Cardinal vowel #1 corresponds to the position of the front part of the tongue razed the gradual lowering of the tongue lowest position gives another point for cardinal point #5. The lowest front position of the tongue gives the point for cardinal #4. The upper back limit for the tongue position gives the point for cardinal #8. This position for cardinal vowels #1, 4, 5, 8 were copied from x-ray photographs the tongue positions between this points x-ray and equidistant points for #2, 3, 6, 7 were found. The symbols for the eight cardinal vowels are: 1 -i, 2 - e, 3 - ε, 4 - a, 5 - ^, 6 - o, 7 – o:, 8 - u .
Acoustically vowels differ due to their tembral coloring, each vowel is characterized by its own formants. Russian phoneticians suggest a classification of vowels according to the following principals: 1) position of the lips; 2) position of the tongue; 3) degree of tenseness and the character of the end; 4) length; 5) stability of articulation.1. rounded u-u:; o-o: and unrounded; 2. Horizontal movements of the tongue: back vowels – when the bulk of the t moves backwards, the back part of the t is raised towards the soft palate: fully back (o-o:,u:, oi), back advanced (u, a: ); front vowels- when the bulk of the t moves forward, the front part of the t is raised towards the hard palate: fully front ( i:, e, ei), front- retracted ( I, au, ai), central (^). Vertical movements of the t: high: narrow variation (i:, u: )/ broad v (I,u); mid: n/b; low: n/b. 3. Long vowels – tense (when the muscle of the lips, tongue, cheeks, back walls of pharynx are tense) i: u: D. Jones. Short vowels – lax (when the organs are relatively relaxed). Acc to the character of the end: checked (occur in stressed syllables ending in a fortis voiceless cons /bet/ /ka:t/; unchecked – occur terminally/ are followed by a lenis voiced cons /a:/ in /ka:d/. 4. Long and short. Length may depend on the number of factors: position of a vowel in the word (tie-tied-tight); word stress- vowel is longer in stressed syllable than in unstressed (fOrecast-N, forecAst- V-shorter); the number of syllables in the word- in polysyllabic words vowels are shorter (verse-universe); the change of the syllabic structure- in words with open type of syll the vowels are longer than in words with closed type of syll; sonority- vowel of low sonority are longer than vowel of greater sonority (/I/ is longer than /o/, /i:/ is longer than /a:/); the tempo of speech- the higher the rate of sp, the shorter the vowels.5. Not singled out by Br and Am phoneticians. Monophthongs (simple vowels)- pure unchanging vowel sound, organs of sp don’t change the position. Diphthongs (complex vowels) – complex sound, which consists of 2 elements and the are pronounced to form a single syllable. The organs of sp start in the position of the 1^st vowel and they glide to the position of the 2^nd vowel.