Multiresolutional modification of speech signals for listeners with hearing impairment

A new method, the multiresolutional modification algorithm (MMA), which mod ifies speech signals in frequency and time domains, is proposed for listene rs with hearing impairment and early clinical results are reported. Unlike other methods, this algorithm modifies the wavelet coefficients of the spee ch signal in order to obtain a modified version of the original signal inst ead of modifying the speech waveform itself. The speech signal is first div ided into subbands using an Ii-level quadrature mirror filter (QMF) bank. T hese subbands are then modified using the modification algorithm. Finally, the inverse Wavelet transform is applied to these modified subband coeffici ents in order to reconstruct a modified version of the input signal. The ef ficacy of the MMA was evaluated using subjects with hearing impairment and subjects with no such impairment. Listening tests showed that the proposed algorithm increases the quality and intelligibility of the modified speech over the well-known modification algorithms.