(As a further experiment, I’ve coded this posting in such a way that it should appear in the font Segoe UI for those who have it. Those who don’t, but have Lucida Grande, will see that. Those who have neither will see their default font.)
There’s an old limerick that goes like this.
ðə ˈwɒz ə jʌŋ ˈmæn əv kælˈkʌtə
əˈflɪktɪd ət ˈtaɪmz wɪð ə ˈstʌtə —
hi ˈsed pəpəˈpliːz
wʊdʒu ˈpɑːs mi ðə ˈtʃiːz
ən ðə ˈbəbəbəˈbəbəbəˈbʌtə.
I wouldn’t normally use this even for exemplification nowadays, not only because Calcutta has been renamed Kolkata (Bengali কলকাতা ˈkolkat̪a) but also because we know that we should not mock the afflicted.
However it does illustrate an interesting phonetic point. The issue is whether the STRUT vowel and the schwa are allophones of the same phoneme (realizations of the same underlying phonological unit) or not.
Some would claim that this is a non-issue, because STRUT is always stressed and schwa is never stressed. This argument might work if we define stress lexically, but it will not hold if by stress we mean a rhythmic beat in running speech.
The advantage of using a strongly rhythmic verse form such as the limerick is that we hold the rhythm constant as we play around with vowel qualities. And in my speech I feel, and believe I make, a clear difference between the last line as transcribed above and two other possibilities,
ðə ˈbʌbʌbʌˈbʌbʌbʌˈbʌtə and
I can, if I choose, produce both ə and ʌ either stressed or unstressed.
There are though, I know, many other speakers who would not feel able to make any such distinction. They are the people who think of above as having the same vowel sound in each syllable.
This is what I referred to in Accents of English as ‘the STRUT-Schwa Merger’, adducing such variably distinct pairs as an orthodoxy vs unorthodoxy and a large and tidy room vs a large untidy room. It is presumably responsible, via restressing, for the AmE strong forms of of and from (compare BrE ɒv, frɒm).