September 22-25, 1997
The method of spectral subtraction has become very popular in speech enhancement. It is performed by modifying the spectral amplitudes of the disturbed signal. The spectral analysis of the signal is usually done by a Discrete Fourier Transformation (DFT). We propose a spectral transformation with nonuniform bandwidth to take into account the characteristics of the human ear. The spectral analysis and synthesis is performed by a non-critically decimated discrete wavelet transform. Critical subsampling is not performed to avoid errors due to aliasing. A significant drawback of spectral-subtraction methods are tonal residual noises in speech pauses with unnatural sound. The application of the proposed wavelet transform results in reduced residual noise with subjectively more comfortable sound.
Bibliographic reference. Engelsberg, Andreas / Gulzow, Thomas (1997): "Spectral subtraction using a non-critically decimated discrete wavelet transform", In EUROSPEECH-1997, 2559-2562.