Navajo vowel formants.

The graphing the first and second formants of a vowel roughly corresponds to its perceived location on a vowel chart.

Formant data from McDonough et al. (1993).

First formant (F1) is plotted against the difference between the second and first formants (F2-F1). Formant measurements are in Hz. The frequencies have been converted to a mel scaling (the equation is ${\displaystyle mel=(1000/\log _{10}2)(\log _{10}(1+frequency/1000))\ }$, which is from Fant (1968)).

The F2-F1 vs. F1 plotting (over a F2 vs. F1 plotting) is suggested by Ladefoged (1993). The mel scaling suggestion is from Ladefoged (1967). McDonough's formant values are found here: Navajo phonology: Vowels: Acoustic phonetics.

Bibliography:

• Fant, Gunnar. (1968). Analysis and synthesis of speech processes. In B. Malmberg (Ed.), Manual of phonetics (pp. 173-177). Amsterdam: North-Holland.
• Ladefoged (1967). Three areas of experimental phonetics. London: Oxford University Press.
• Ladefoged (1993). A course in phonetics (3rd ed.). Fort Worth: Harcourt Brace College Publishers.
• McDonough, Joyce; Ladefoged, Peter; & George, H. (1993). Navajo vowels and universal phonetic tendencies. University of California Working Papers in Phonetics, 84, 143-150.