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Abstract : |
Abstract Use of a bilinear conformal map to achieve a frequency warping nearly identical to the Bark scale is described. Because the map takes the unit circle to itself, its form is that of an allpass transfer function. Since it is a first-order map, it preserves the model order of rational systems. A direct-form expression for computing the optimal allpass coefficient as a function of sampling rate is developed, and a filter design example is presented. 1 Introduction With the increasing use of frequency-domain techniques in audio compression, there is increasing emphasis on psychoacoustic based spectral measures [4]. One of the important spectral transformations for audio is warping to the Bark frequency scale. Based on the results of many psychoacoustic experiments, the Bark frequency scale is designed so that the critical bands of human hearing are uniform in size [1, 2]. The bilinear conformal map, defined by the substitution, |
