Comparison of Bob Cunningham's vowels with vowels from Ladefoged

Click here to see explanatory notes.

Explanatory notes:

• The symbols on the chart are as defined in Evan Kirshenbaum's ASCII IPA.
• Symbols in blue represent sounds spoken by Bob Cunningham. They are selected from the twelve vowels whose formants are plotted at "Twelve vowels".
• Symbols in red represent values taken from a chart in Kirsten Malmkjaer's The Linguistics Encyclopedia, page 7, in a paper written by Chin-W. Kim, where they are attributed to "Ladefoged, 1982, page 279".
• Kirsten Malmkjaer's The Linguistics Encyclopedia is ISBN 0-415-02942-2 (hbk), 0-415-122566-9 (pbk). Selection and editorial matter copyright Kirsten Malmkjaer. Individual entries copyright the authors.
• I've constructed the grid from measurements of Figure 10, page 7, in The Linguistics Encyclopedia. The scales are not linear and they're not exactly logarithmic. If anyone can tell me what mathematical relationship they represent, I would greatly appreciate it. Ladefoged probably explains the scales in his 1982 book, which I don't have.
• "Ladefoged 1982" is "Ladefoged, P. (1982), A Course in Phonetics, 2nd edn, New York, Harcourt Brace Jovanovich".
• I've used Windows 3.1 Paintbrush to place the values on the chart. I'm not fully satisfied with the accuracy of placement I've been able to achieve by this means, but I feel that the locations are close enough to satisfy the intended purpose of the chart.