... 12 High vowels: / i:, i , ʊ, u: / Middle vowels: / e,ɔ, ɜ:, ə/ Low vowels: / æ, ʌ, ɒ,a:/ According to the front /back of the tongue: Front vowels: / i:, i, e, æ/ Central vowels: /ʌ, ... ə/ Back vowels: /ɒ, u:, ʊ, ɔ:,a:/ According to the lips rounding: Rounded vowels: /ɒ, u:, ʊ, ɔ:/ Unrounded /spread vowels: /ʌ, ɜ:, ə,a/ Neutral vowels: /e,i, i:,æ/ Diagram of vowels classification ... produced rapidly and without interruption. 2.2. Classification of vowels: There are 20 vowels in English sound system including 12 pure vowels & 8 diphthongs plus 5 triphthongs. *Monothongs:...