Institute for Systems Research

A fundamental conclusion arising from this analysis is that spectral peaks are represented along two largely independent axes: the magnitude and phase of their Fourier transforms. More specifically, it is argued that, along these two dimensions, the auditory system analyzes an arbitrary spectral pattern in a localized Fourier transform domain. This is closely analogous to spatial frequency transformations in the visual system. Within this general framework, we propose a model of profile analysis in which a spectral profile is represented by a weighted sum of sinusoidally modulated spectra (ripples). The first part of the analysis is performed by a bank of bandpass filters, each tuned to a particular ripple frequency and ripple phase. The parameters of the model are estimated using data from several ripple discrimination experiments. The second part of the model is a detection stage which operates on the magnitude and phase of the computed transform, and varies with the type of perceptual task. The results of the detection operations are compared to experimental data from various profile analysis tasks. The model accounts well for the perceptual results in these tests. We propose two types of psychoacoustical experiments involving any arbitrary spectral patter, which should further verify the predictions of the model.