ASA 127th Meeting M.I.T. 1994 June 6-10

4pSP29. Fundamental frequency effects on thresholds for vowel formant discrimination.

Dept. of Speech and Hear. Sci., Indiana Univ., Bloomington, IN 47405

In a recent report, thresholds for discrimination of vowel formants are described as a piecewise-linear function that is flat in the F1 region and linearly increasing in the F2 region [Kewley-Port and Watson, J. Acoust. Soc. Am. 95, 485--496 (1994)]. Results also suggested a trend for higher fundamental frequency to produce increased formant thresholds for these synthetic female vowels. Further study of the effect of various stimulus parameters on formant thresholds is needed to describe discrimination using excitation pattern models. The present experiment investigated the effect of glottal source on formant thresholds in synthesized male vowels. Thresholds for formant-frequency discrimination were obtained for six vowels with two fundamental frequencies: High (126 Hz) and low (101 Hz). Four well-trained subjects performed an adaptive tracking task under minimal-uncertainty conditions. Discrimination thresholds for vowels with high F0 were significantly greater than those with low F0. Consistent with results for female vowels, thresholds for frequencies below 800 Hz in the F1 region appeared relatively constant while thresholds in the F2 region were increasing. There was a general trend across all male and female vowels for higher fundamental frequency to result in increased discrimination thresholds. [Research supported by NIDCD and AFOSR.]