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Department of Linguistics


American English Monophthongs

Robert Mannell

American English shows a much greater degree of regional variation than does Australian English. For example, Olive et al (1993, p362) divide the United States into ten dialect regions (which in turn may each have some additional internal variation). As a consequence, it is not desirable to attempt to define a "General" American English (as has been done for Australian English). Instead, on this page and the associated page on American English Diphthongs a couple of regional dialects have been chosen. The Midwestern variety is described by Ladefoged (1999) as being more "conservative" than the Californian variety in that it has maintained a greater number of vowels.

In particular, Ladefoged's descriptions of these two dialects (1993, 1999) imply (but do not explicitly state) that in Californian English there has been a monophthongisation of two of the diphthongs still found in Midwestern American English, that is /eɪ/ and /oʊ/. Furthermore, during this process, the diphthong /oʊ/ has merged with the monophthong /ɔ/. This has resulted, relative to Midwestern American English, in two fewer diphthongs in Californian English but only one additional monophthong.

Ladefoged (1999) further indicates that the process of monophthongisation in Californian English is not complete as both original diphthongs are still pronounced with an offglide. This has been indicated in the phonetic representation of each of these two vowels on the appropriate diagram, above.

In the above diagrams, the sample words are different from those used in the diagrams of the other English dialects that are illustrated on accompanying pages. This is because American English is a rhotic dialect of English and a post-vocalic /r/ has a significant effect on the actual realisation of its preceding vowel (Olive et al, 1993). Wherever possible, words that do not include a post-vocalic /r/ have been used.

Another consequence of the difference between rhotic and non-rhotic dialects of English is that in rhotic dialects such as American English, the centring diphthongs (/ɪə/,/eː,eə/ and ʊə/) are not to be found.

On these diagrams, a phonemic transcription typical of those used by American phoneticians has been indicated in red for each vowel.

See also the page on Distinctive Features: Australian English Vowels for a comparison of Australian and American English vowel features.


  1. Ladefoged, P., A Course in Phonetics (3rd edition), Harcourt Brace, Fort Worth USA, 1993.
  2. Ladefoged, P., "American English", in Handbook of the International Phonetics Association, IPA, Cambridge UK, 1999
  3. Olive, J., Greenwood, A., and Coleman, J., Acoustics of American Speech: A dynamic approach, Springer, New York, 1993