Pitch Ambiguities of Harmonic Two-Tone Complexes

Abstract

A tone complex comprising two arbitrary successive harmonics of low order, presented monotically or dichotically, evokes a pitch sensation which corresponds to the missing fundamental frequency. When the harmonic numbers are higher, the pitch becomes increasingly more ambiguous. These ambiguities are the major cause of incorrect responses when subjects are asked to identify musical intervals played with harmonic tone complexes of relatively high harmonic number. A detailed investigation was made of the particular confusions a subject makes when he responds incorrectly in a musical interval identification test by obtaining confusion matrices for each harmonic number. The results imply a multimodal distribution for pitch with the locations of the modes approximated by the so called “first effect” [J. F. Schouten, R. J. Ritsma, and B. L. Cardozo, J. Acoust. Soc. Amer. 34, 1418 ( 1962)]. Results are compared with theoretical performance predicted by Goldstein's Optimum Processor Theory. [Work supported by grants from the National Institutes of Health.]