Difference limens for complex tones (DLCs) that differ in F0 are widely regarded as a measure of periodicity-pitch discrimination. However, because F0 changes are inevitably accompanied by changes in the frequencies of the harmonics, DLCs may actually reflect the discriminability of individual components. To test this hypothesis, DLCs were measured for complex tones, the component frequencies of which were shifted coherently upward or downward by ΔF = 0%, 25%, 37.5%, or 50% of the F0, yielding fully harmonic (ΔF = 0%), strongly inharmonic (ΔF = 25%, 37.5%), or odd-harmonic (ΔF = 50%) tones. If DLCs truly reflect periodicity-pitch discriminability, they should be larger (worse) for inharmonic tones than for harmonic and odd harmonic tones because inharmonic tones have a weaker pitch. Consistent with this prediction, the results of two experiments showed a non-monotonic dependence of DLCs on ΔF, with larger DLCs for ΔF's of ±25% or ±37.5% than for ΔF's of 0 or ±50% of F0. These findings are consistent with models of pitch perception that involve harmonic templates or with an autocorrelation-based model provided that more than just the highest peak in the summary autocorrelogram is taken into account.
Bibliographical noteFunding Information:
This work was supported by an NIH R01 Grant DC05216. We are indebted to Laurent Demany and Brian Roberts, whose suggestions concerning the design and results of a prior study inspired the current work, to Gavin Bidelman, Peter Cariani, and Bertrand Delgutte for insightful email discussions concerning auditory-nerve and autocorrelation models, and to Peter Cariani, Chris Plack, and two anonymous reviewers for many helpful suggestions on an earlier version of the manuscript.
© 2012 Acoustical Society of America.