Noise‐induced shifts in the pitch of pure and complex tones

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Pitch‐matching experiments were performed between test sounds comprising dichotic harmonic two‐tone complexes or single harmonics, both partially masked by lowpass noise, and a diotic periodic pulse comparison sound. Tones were at 60 dB SPL, and the pitch of the test signal was measured as a function of the intensity of the masking noise. The slope of the resulting pitch functions, expressed in percent pitch shift per dB of noise, was measured for several harmonics and two‐tone complexes, all having a fundamental of 200 Hz. Measurements were also obtained for harmonics in contralateral lowpass noise. Slopes for complex tones were found to be substantially smaller than slopes for pure tones in ipsilateral noise, but about the same as the slopes for pure tones in contralateral noise. This finding is inconsistent with the idea of serial pitch processing (frequency →, spectral pitch → virtual pitch) as found in Terhardt's virtual pitch theory, but supports the notion that pure tone pitch and complex tone pitch are mediated by entirely different mechanisms. [Work supported by NIH, Grant NS11680.]