Small, A.M., Campbell, R.A. (1961). Pitch shifts of periodic stimuli with changes in sound level. J. Acoust. Soc. Am. 33, 1022-1027

Pitch shifts with changes in sound level were investigated for two types of stimuli, one whose pitch was hypothesized to be analyzed on the basis of "place" and the other whose pitch was presumed to be related to "periodicity". Eight subjects made alternate monaural pitch matches with four stimuli; pure-tone, dc pulses (both with energy at the fundamental frequency-place pitch), and two vaarieties of ac pulses (with little energy at the fundamental frequency-periodicity pitch). The fundamental in all cases was approximately 100 cps. Generally, pitch shifts were small, although there were marked differences in the extent and in the variability of the pitch matches as a function of the type of stimulus. Partly because of large differences between subjects, statistically significant shifts were found for only two of the stimuli, one "place" and one "periodicity" stimulus. These shifts were similar in direction, with the pitch shifting downward as level is first increased, then upward with a further increase. Although there appears to be little in the data to support duality of pitch analysis, it is possible that all stimuli were perceived on the basis of periodicity. However, it seems difficult to handle pitch shifts with changes in level within the confines of "periodicity" analysis.