Bionic wavelet transform: A new time-frequency method based on an auditorymodel

In this paper, a new adaptive wavelet transform, named bionic wavelet trans form (BWT), is developed based on a model of the active auditory system. Th e most distinguishing characteristic of BWT is that its resolution in the t ime-frequency domain can be adaptively adjusted not only by the signal freq uency but also by the signal instantaneous amplitude and its first-order di fferential. The automatically adjusted resolution, even in a fixed frequenc y along the time-axis, is achieved by introducing the active control of the auditory system into the wavelet transform (WT). Other properties of BWT i nclude that: 1) BWT is a nonlinear transform that has high sensitivity and frequency selectivity; 2) BWT represents the signal with a concentrated ene rgy distribution; and 3) the inverse BWT can reconstruct the original signa l from its time-frequency representation. In order to compare these three p roperties between BWT and WT, experiments were conducted on both constructe d signals and real speech signals. The results show that BWT performs bette r than WT in these three aspects, and that BWT is appropriate for speech si gnal processing, especially for cochlear implants.