Warped discrete cosine transform cepstrum: A new feature for speech processing

In this paper, we propose a new feature for speech recognition and speaker identification application. The new feature is termed as warped-discrete cosine transform cepstrum (WDCTC). The feature is obtained by replacing the discrete cosine transform (DCT) by the warped discrete cosine transform (WDCT, [4]) in the discrete cosine tranform cepstrum (DCTC [2]). The WDCT is implemented as a cascade of the DCT and IIR all-pass filters. We incorporate a nonlinear frequency-scale in DCTC which closely follows the bark-scale. This is accomplished by setting the all-pass filter parameter using an expression given by Smith and Abel [5]. Performance of WDCTC is compared to mel-frequency cepstral coefficients (MFCC) in a speech recognition and speaker identification experiment. WDCTC outperforms MFCC in both noisy and noiseless conditions.