Inrtoduction

Long vowels in the IPA are:
/i:/ week /wi:k/, feet /fi:t/, media /ˈmiː.di.jə/
/ɑ:/ hard /ha:/, park /pa:k/, article /ɑː.tɪ.kəl/
/ɔ:/ fork /fɔ:k/, walk /wɔ:k/, August /ɔːˈɡʌst/
/ɜ:/ heard /hɜ:d/, word /wɜ:d/, surface /ˈsɜː.fɪs/
/u:/ boot /bu:t/, group /gru:p/, beautiful /ˈbjuː.tɪ.fəl/
Diphthong vowels (double) in the IPA are:
/eɪ/ place /pleɪs/, late /leɪt/, dangerous /ˈdeɪn.dʒə.rəs/
/oʊ/ home /hoʊm/, phone /foʊn/, global /ˈɡloʊ.bəl/
/aʊ/ mouse /maʊs/, brown /braʊn/, accountant /əˈkaʊn.t̬ənt/
/ɪə/ clear /klɪə/, fear /fɪə/, career /kəˈrɪə/
/eə/ care /keə/, wear /weə/, declare /dɪˈkleə/

1.2. Classification of English vowel sounds
Classification of Vowels
Vowels are normally made with the air stream that meets no obstruction in the mouth, pharyngeal and nasal cavities.
On the articulatory level the description of vowels notes changes:

1. 
   in the stability of articulation
   
2. 
   in the tongue position
   
3. 
   in the lip position
   
4. 
   in their length
   

The stability of articulation
Monophthongs, diphthongs, and diphthongoids are the three categories of vowels in the English language. Monophthongs are vowels that virtually always have the same articulation. They are I e a: o o: U e a: u u: ]. When pronouncing diphthongs, the vocal folds move smoothly from one vowel position to the next within a single syllable. The nucleus, which serves as the foundation, is solid and distinct. These are them: [ei ai oi au u I u] While the articulation of diphthongoids is slightly changing, there is less of a distinction between the beginning and the end than there is with diphthongs. These are they: [i: u:]
Tongue Position
The tongue may move forward, backward, up, down, thus changing the quality of vowels.

1. 
   When the tongue is in the front part of the mouth and the front part of the tongue is raised to the hard palate a front vowel is pronounced.They are – [i: e ǽ]
   
2. 
   A front-retracted vowel is produced when the tongue is in the front part of the mouth, but slightly retracted, and the section of the tongue closer to the center than the front is lifted. It is - I
   

3. The vowel is referred to be central when the front of the tongue is lifted toward the back of the hard palate. They are [[:]].
4. A back vowel is uttered when the tongue is in the back of the mouth and the back of it is raised toward the soft palate. These people are [a: o o: u:]. Back-advanced vowels are spoken when the tongue is in the back of the mouth but is slightly advanced and the middle portion of it is lifted toward the front part of the soft palate. It is - [U]. The tongue may be lifted to various heights toward the roof of the mouth as it moves up and down in the mouth.
1. A vowel is said to as near when the front or rear of the tongue is lifted high toward the palate. These people are I I u u:]. 2. Open vowels are uttered when the front or rear of the tongue is as low in the mouth as feasible. They are [a: o: o] 3. Mid vowels are spoken when the uppermost section of the tongue is in the position halfway between the close and the open position. They are - [e:]. Lip Placement Vowels are referred to as unrounded when the lips are neutral or wide. They are: I I e a: a: a: a: a: a: a]. The vowel is referred to as rounded when the lips are brought together so that the space between them is more or less rounded. These people are: [o o: u u:]