A Matlab Toolbox for Efficient Perfect Reconstruction Time-Frequency Transforms with Log-Frequency Resolution

Abstract

In this paper, we propose a time-frequency representation where the frequency bins are distributed uniformly in log-frequency and their Q-factors obey a linear function of the bin center frequencies. The latter allows for time-frequency representations where the bandwidths can be e.g. constant on the log-frequency scale (constant Q) or constant on the auditory critical-band scale (smoothly varying Q). The proposed techniques are published as a Matlab toolbox that extends [3]. Besides the features that stem from [3] – perfect reconstruction and computational efficiency – we propose here a technique for computing coefficient phases in a way that makes their interpretation more natural. Other extensions include flexible control of the Qvalues and more regular sampling of the time-frequency plane in order to simplify signal processing in the transform domain.