Beatriz Cabrera Portillo asks about the American English chart, and also about the vowel sound /ɑː/. She says:
1) When comparing your magnificent two phonemic charts in both BrE and AmE, I’ve realised that a “long a” is not included in the American chart. Parallel to this, the group of dipthongs ending in “schwa” are not inserted in the American chart either.
2) As the “a” sound is not analysed in your blog and after researching in several resources, I am a bit doubtful about the position of the mouth in the vowel articulation of words like but as opposed to it in words such as car. Is it possible to say that both sounds share the same mouth position with the only difference in the length? Thanks in advance. Beatriz
Thanks for your comments Beatriz. Yes, it’s interesting to compare the BrE and AmE charts. There are several noteworthy differences, two of which you have pointed out.
Length marks are not normally indicated in AmE learner dictionaries, (eg the Macmillan English Dictionary) not because AmE vowels cannot be long, as they certainly vary in length, but because length is considered a less predictable way of identifying a vowel sound as being one phoneme or another. So, as you point out /ɑː/ on the BrE chart becomes /ɑ/ on the AmE chart. Furthermore the sound /ɒ/ (as in hot) on the BrE chart does not appear on the AmE chart, that sound merging mostly with AmE /ɑ/ and occasionally with /ɔ/.
The three ‘weak’ diphthongs of BrE, that is the ones that glide to schwa /ǝ/, likewise are not considered part of the phonemic set of Standard AmE and so do not appear on the AmE chart. Again, see the MED for learners of American English.
Regarding BrE / ʌ/ and /ɑː/, no they do not share the same mouth position. Length is a factor, but the vowels have a different acoustic quality. Put briefly, the centre and back of the tongue needs to be lower for /ɑː/ than for / ʌ/ . Thus the tongue is positioned differently, and consequently /ɑː/ has a greater volume of vibrating air in the mouth above the tongue.
I intend before too long to get onto the remaining vowel sounds in the continuing Story of Sounds …. Meanwhile, I hope this is of use…. Adrian