WOLA Filter Bank Design Requirements in Hearing Aids

Abstract

This paper deals with the design of DFT-based filter banks for hearing aids, where spectral modifications are necessaries to compensate hearing loss. The WOLA (Weighted Over-Lap Add) filter bank is considered. It is an efficient implementation of the DFT filter bank to carry out short-time analysis, which is sometimes included as a core in digital signal processors for hearing aids. The relation between analysis and synthesis windows in order to obtain perfect reconstruction if spectral modifications are not necessary, are studied. Some length constraints of the filters impulse responses, and the number of bands of the filter bank are established, in order to avoid time domain aliasing.