Pitch and the perceptual organization of complex spectra.

The psychological attribute of pitch is the most important organizing element by which the human auditory system reduces a steady-state complex signal to one or more perceptual entities. Historically both experimental and theoretical studies of pitch perception have been primarily concerned with the synthetic listening mode and the pitch of a single entity. However, there are experiments which test the analytic mode and the ability to segregate several entities. The mistuned harmonic experiment, in which the task is to hear out a mistuned partial in a complex tone, is a promising approach of this kind, though it demands that the experimenter try to distinguish those effects which are due to beats of mistuned consonances or nonlinear combination tones from those due to perceptual reorganization into segregated entities. The results of mistuned harmonic experiments suggest that the most sensitive segregation operation is mediated by neural processes which are tonotopically local, though they are tuned more broadly than a critical band. Therefore, appropriate models are not based upon pattern matching in a central spectrum but upon cross correlation between the firing patterns in neighboring sharply tuned neural elements or upon autocorrelation of the pattern in a more broadly tuned element. Such models are supported and constrained by physiological observations of the temporal response to complex tones in single cells of the eighth nerve, the cochlear nucleus, the inferior colliculus and the cortex. [ABSTRACT FROM AUTHOR]