Speech enhancement using warped discrete cosine transform

In this paper, we propose an approach to enhance the degraded speech under background noise environments based on the warped discrete cosine transform (WDCT). For developing an effective expression of 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 the analysis of 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.