Speech enhancement using warped discrete cosine transform

We propose an approach based on the warped discrete cosine transform (WDCT) to enhance degraded speech under background noise environments. To develop an effective expression for the frequency characteristics of the input speech, we apply a variable frequency warping filter to the conventional discrete cosine transform (DCT). The frequency warping control parameter is adjusted according to an analysis of the spectral distribution in each frame. For a more accurate analysis of spectral characteristics, we employ the split-band approach while the global soft decision for speech presence is performed in each band separately. A number of tests show that the WDCT-based enhancement method yields better performance than the DCT-based algorithm.