Dennis L. Hughes
Randy L. Diehl
Dept. of Psychol., Univ. of Texas, Austin, TX 78712
Hoemeke and Diehl [J. Acoust. Soc. Am. 93, 2422(A) (1993)] reported that the perceptual boundary between [+high] and [-high] English vowels occurs at an F[sub 1]--F[sub 0] distance of 3--3.5 Bark and that this boundary is sharper than those for other height contrasts. This suggests that the 3- to 3.5-Bark distance, corresponding to the range of the ``center of gravity'' effect [L. Chistovich and V. Lublinskaja, Hear. Res. 1, 185--195 (1979)], affords a perceptually natural boundary. In the current study, listeners performed a 0.5-Bark step F[sub 1]--F[sub 0] discrimination task on one of five series of single formant stimuli. F[sub 1] ranged from 2.5--7.0 Bark within a series, and F[sub 0] ranged from 1.0--2.0 Bark between series. Significant linear effects of both a formant/harmonic interaction (r=0.68) and F[sub 1]--F[sub 0] distance (r=0.71) were found (multiple R[sup 2]=0.94). However, a peak in discriminability near F[sub 1]--F[sub 0]=3--3.5 Bark was not observed. Thus the relatively sharp [+high]/[-high] boundary does not appear to be owing to enhanced discriminability. [Work supported by NIDCD.]