Riska Amelia

Vowels are produced when there is NO OBSTRUCTION of the out-going air from the lungs and pharynx. There are 12 vowels in English:
-SHORT  VOWELS
  [I] [e] [ɒ] [ʊ] [ʌ] [ə] [æ]
-LONG VOWELS
  [i:] [ɔ:] [a:] [u:] [ə:]

VOWEL DIAGRAM

2.      DIPHTHONGS

Diphthongs is a complex speech sound or glide that begins with one vowel and gradually changes to another vowel within the same syllable. There are 2 kind of diphthongs:

-CLOSING

  [eI] [aI] [aʊ] [oʊ] [oI]
-CENTERING