American English Phonetics

6.3.8 GA /ʌ/ and /ə/

GA /ʌ/ is a central, half-open, unrounded vowel. It’s often assumed that the only difference between /ʌ/ and /ə/ is that /ʌ/ occurs in strong syllables and /ə/ in weak syllables. However, /ʌ/ is considerably more open. Although /ʌ/ is a lax vowel, it is quite long.

Advice for Dutch learners:
Dutch learners often have difficulty in hearing and making the difference between /ʌ/ and /ɑː/. One thing you must make absolutely sure of is that you know where which phoneme is used. Note that /ʌ/ is usually spelled “u” or “o” as in cup and love, and /ɑː/ usually “a” and “o”. The spelling “o”, therefore, is likely to give you cause to go to the LPD.

For /ʌ/, try and use the quality of the AN /ɑ/ of Adje, and use it in duller.
For /ɑː/ open the mouth wide, and make a really open back vowel. Try it in dollar.

Here are some minimal pairs with /ɑː/ and /ʌ/: Practice saying them.

ɑː	ʌ
sock /sɑːk/	suck /sʌk/
hot /hɑːt/	hut /hʌt/
not /nɑːt/	nut /nʌt/
cotton /ˈkɑːt̬ən/	cuttin’ /ˈkʌt̬ɪn/
pot /pɑːt/	putt /pʌt /
dock /dɑːk/	duck /dʌk/
shot /ʃɑːt/	shut /ʃʌt/
robber /ˈrɑːbər/	rubber /ˈrʌbər/

Weak /ə/ is short. lts quality is central unrounded, and ranges from half-close to half-open, depending on context. Before palato-alveolars and velars, it is closish, and, particularly before velars, it can be interpreted as /ɪ/. In word-final position, it is openish, and may be close to the usual quality of /ʌ/, as in villa, Amanda.