Pitch of dichotically delayed noise and its possible spectral basis.

Abstract

Pitch can be signalled by interaural differences in timing, but it is unknown how the intercochlear timing mediates pitch. Pitch of complex tones can be well understood in terms of a central pitch mechanism that reads across the frequencies of a centrally presented spectrum. We consider whether pitch phenomena signalled by binaural timing are also compatible with auditory processing through tonotopic organization. Known binaural pitch phenomena produced by stimuli comprising two wideband Gaussian noise sources, each with different interaural delay were examined. The major findings are that (i) a single noise source with interaural delay τ is adequate to produce a pitch corresponding to 1/τ, (ii) the medially lateralized pitch image is little affected by the addition of a second independent noise source presented in antiphase, (iii) the dichotic pitch is similar to monaural repetition pitch, for which the stimulus to the ear comprises a noise source added to its delay, and (iv) the image of dichotic repetition pitch is much more faint and compact than that of monaural repetition pitch. Durlach's [J. Acoust. Soc. Am. 34, 1096–1099 (1962)] equalization and cancellation model of binaural signal detection is adapted to describe the compatibility between the binaural pitch phenomena and auditory mediation of pitch by central spectral patterns.