On the use of discrete cosine transform in cepstral analysis

If the original signal is defined to be symmetrical, the discrete Fourier transform (DFT) used in cepstral analysis can be replaced by a discrete cosine transform (DCT). This principle is applied to the evaluation of the real and complex pseudocepstrum of speech signals. In both the real and complex cepstrum cases, it is found that the use of the DCT does not degrade the information contained in the cepstrum while substantially reducing the computational complexity.