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.