Representation of Spectral Profiles in the Auditory System, II: Detection of Spectral Peak Shape Changes

Based on the ripple analysis model outlined in Part I of this paper, predictions are made for the detection of shape changes in spectral peak profiles. Peak shape is uniquely described in terms of two parameters: bandwidth factor (BWF) which reflects the tuning or sharpness of a peak, and a symmetry factor (SF) which roughly measures the local evenness or oddness of a peak. Using profile analysis methods, thresholds to changes in these parameters (defined as dBWF/BWF and dSF) are measured together with the effects of several manipulations such as using different peak levels, varying spectral component densities, and randomizing the frequencies of the peaks. The new ripple analysis model accounts well for the measured thresholds. Predictions of the three previously published models for the same profiles are also evaluated and discussed