A model of profile analysis is proposed in which a spectral profile is assumed to be represented by a weighted sum of sinusoidally modulated spectra (ripples). 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 ripple detection experiments in [Green} 1986; Hillier 1991]. Detection thresholds are computed from the filter outputs and compared with perceptual thresholds, for profile detection experiments with step, single component increment, and the alternating profiles. The model accounts well for the measured thresholds in these experiments. Physiological and psychophysical evidences from the auditory and visual systems in support of this type of a model are also reviewed. The implications of this model for pitch and timbre perception are briefly discussed.