A bio-inspired companding strategy for spectral enhancement

This work presents a compressing-and-expanding, i.e., companding, strategy for spectral enhancement inspired by the operation of the auditory system. The companding strategy simulates the two-tone suppression phenomena of the auditory system and implements a soft local winner-take-all-like enhancement of the input spectrum. It performs multichannel syllabic compression without degrading spectral contrast. The companding strategy works in an analog fashion without explicit decision making, without the use of the fast Fourier transform, and without any cross-coupling between spectral channels. The strategy is useful in cochlear-implant processors, hearing aids, and speech recognition for enhancing spectral contrast. It is well suited to low-power analog circuit implementations.