ASA 125th Meeting Ottawa 1993 May

5aPP7. Effect of stimulus intensity on the pitch of a complex tone's spectral edge.

Adrianus J. M. Houtsma

Armin Kohlrausch

Peter A. Kef

Inst. for Percept. Res./IPO, P. O. Box 513, 5600 MB Eindhoven, The Netherlands

Six subjects made pitch matches between a fixed-intensity sinusoidal comparison tone and a complex test tone with harmonics 1 through 20 in zero-phase and fundamentals between 46 and 54 Hz at sensation levels between 10 and 70 dB. Tone and intertone gap durations were 500 ms. All subjects performed six matches at all five fundamental frequency values and at seven intensities. As control, subjects also matched pitches between pure tones around 1000 Hz. Mean matches to complex tones were found to depend on intensity, at a subject-averaged rate of 0.12% dB, always going from a pitch below the edge frequency at low sensation level to a pitch above the edge frequency at high sensation level. This is consistent with evidence from cochlear nerve data by Evans [Philos. Trans. R. Soc. London Ser. B 336, 381 (1992)]. Standard deviations of complex-tone matches were typically only a factor two larger than those of pitch matches between pure tones, even at the lowest sensation levels. This is not well understood in terms of cochlear nerve data which suggest that edge pitch should fade away at sensation levels below 30--40 dB [Horst et al., J. Acoust. Soc. Am. 78, 1898--1901 (1985)].