The back vowels u There are five back vowels in english: /a:/,/3:/,//,/u:/,/u/ /a /is a long open, unrounded back vowel /: /is a long half-open, rounded back vowel. It is slightly tense //is a short, open, rounded, lax back vowel /u: /is a long, Close, rounded, tense back vowel /u is a short half-close rounded lax back vowelThe Back Vowels ◼ There are five back vowels in English: /a:/, /ɔ:/ , /ɔ/, /u:/, /u/. /a:/ is a long, open, unrounded back vowel. /ɔ:/ is a long, half-open, rounded back vowel. It is slightly tense. /ɔ/ is a short, open, rounded, lax back vowel. /u:/ is a long, close, rounded, tense back vowel. /u/ is a short, half-close,rounded, lax back vowel