Valter Ciocca
Dept. of Speech & Hearing Sciences, Univ. of Hong Kong, 34 Hospital Rd., Hong Kong
This study investigated how pitch perception mechanisms integrate acoustic information over time. The pitch matching procedure developed by Moore et al. [J. Acoust. Soc. Am. 77, 1853--1860 (1985)] was used in order to measure pitch shifts in a harmonic series (target complex) produced by mistuning a harmonic that either preceded or followed the target complex. In the first experiment, the mistuned component could either stop as the target complex started (pretarget condition) or start as the target stopped (post-target condition). The results showed that pitch shifts were significantly larger in the post-target than in the pretarget condition. In the second experiment, the duration of the silent period, which separated the mistuned component and the target complex, was varied in both the pre- and the post-target conditions. Pitch shifts were virtually eliminated by a delay longer than 20 ms in the pretarget condition. By contrast, a delay of 160 ms was necessary to eliminate pitch shifts in the post-target condition. These results suggest that pitch perception mechanisms take into account the order of occurrence of acoustic information for calculating the pitch of a complex sound. [Work supported by Hong Kong RGC, Grant HKU 362/94M.]