Relation between Critical Bands in Hearing and the Phase Characteristics of Cubic Difference Tones
Manfred R. Schroeder · The Journal of the Acoustical Society of America · 1969
The measured amplitude and phase characteristics of aural cubic difference tones are difficult to account for solely by known mechanical processes in the ear. The frequency selectivity implied by these characteristics considerably exceeds that of the middle and inner ears, even when the selectivity of the basilar membrane is augmented by a traveling-wave model for nonlinear distortion components. On the other hand, the frequency selectivity implied by the phase characteristics of the cubic difference tone is found to correspond closely to the well-known critical bandwidths of hearing. Thus, the sharpening mechanism responsible for the formation of the critical bands may also be responsible for the formation and perception of cubic difference tones. New phase measurements, with a well-defined phase reference, show that the auditory nonlinearity giving rise to cubic difference tones must be an amplitude-limiting nonlinearity if it occurs in an excitatory channel (or an amplitude-expanding one if it is located primarily in an inhibitory pathway).