Note carefully that the vowels A in "vacate" and O in "so" shown on this chart, and the long I in "by" as well as the OU in "out" are almost always diphthongs, not single sounds, and only the first part of the A and O diphthongs is charted above. Diphthongs involve gliding pitches.

The pitches shown above are averages, which may vary as much as three quartertones in either direction. In the charts compiled by some experts in this field, bands of frequencies are shown, rather than single frequencies. While only twelve vowel-sounds are given above, most speakers of English will use sixteen or more vowel-sounds, not counting fine shades of sound and not counting elements of diphthongs. British and American authorities do not agree on the characteristic frequency-bands (often called formants) of certain vowels, and besides this there are many regional variations.

It is not practicable to show those sounds which British speech has and American speech lacks, or vice versa. Examples would be found in such words as not, murmur, pitying, possibility, power, shore, piper, etc. Incidentally, these and other problems are hampering the development of automatic speech recognition machines and robot stenos.

To hear the vowel-pitches in your own personal version, whisper the keywords given above, drawling them out. You might also try reading some familiar poetry in a "stage-whisper"--or better still, listen to someone else doing it.

Compiled by Ivor Darreg from various sources in 1953; revised 1972.