Neurobiology of Harmony Perception

This chapter reports the neurophysiological, neurological, and psychoacoustic evidence to support the contentions that pitch relationships among tones in the vertical dimension influence consonance perception and consonance cannot be explained solely by the absence of roughness. It introduces the terminology and basic psychoacoustics pertinent to the subsequent discussion of experimental results. It then shows that the harmonic relationships of tones in musical intervals are represented in the temporal discharge patterns of auditory nerve fibres. It critically reevaluates the psychoacoustic literature concerning the consonance of isolated intervals and chords, paying particular attention to the relationships among interval width, roughness detection thresholds, and consonance ratings and the predictions of roughness-based computational models about relative consonance as a function of spectral energy distribution. Finally, it describes the evidence that impairments in consonance perception following auditory cortex lesions are more likely to result from deficits in pitch perception than to deficits in roughness perception. This evidence highlights the dependence of so-called low-level perceptual processing on the integrity of the auditory cortex, the highest station in the auditory nervous system.