In (non-rhotic) British English there seem to be two major allophones of the phoneme /ə/. The first which can be heard in potato, career or the weak form of from as an [ə].
However, there's also a second allophone which it appears doesn't get much attention throughout the scientific literature. In fact, I have only found information about it in Gimson's Pronunciation of English (7th edition):
In final positions, e.g. in 'mother, doctor, over, picture, China', the vowel may be articulated in the open-mid central position (= [ə̞]). The acoustic formants of /ə/ are, therefore, likely to be similar to those for /ɜː/ or /ʌ/ according to the situation.
Note: [ə̞] (= lowered [ə]) is meant to be [ɜ] on the IPA vowel chart.
But what about compound words like motherhood, internet, interstellar and so on? Do these also take the somewhat lowered schwa as if they were single words?
Best Answer
I think you're right about the distinction, whichever IPA symbols are appropriate. In younger London speech, final schwa may be closer to /ɑ/, so 'mother' may be pronounced /ˈmʌðɑ/. But the same speaker would probably say 'potato' as /pəˈtɑɪtɑʊ/ with the traditional schwa in the first syllable.