DCT based pseudo complex cepstrum

Muralishankar, R and Ramakrishnan, AG (2002) DCT based pseudo complex cepstrum. In: 2002 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '02)., May 13 - 17, 2002, Orlando, Florida, USA, Vol.1 521-524.

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Abstract

We propose two algorithms, which effectively use Discrete Cosine Transform (DCT) to obtain complex cepsrrum, which we call as the Discrete Cosine Transformed Cepstrum (DCTC), The first algorithm uses the relation between Discrete Fourier Transform (DFT) and DCT 15. Computing the complex cepstrum usingFoiirier Transform needs unwrapped phase. The calculation of the unwrapped phase is sometimes difficult due to the ptesence of multiple zeros and poles near or on the unit circle. Since DCT is a real function, its phase can only be 0 or 7r and phase unwrapping is done by representing negative by exp(—jir) and positive by 1. The motivation for the second algorithm is to obtain DCTC by representing DCT sequence itself by magnitude and phase components. Phase unwrapping is performed in the same way as in the case of first algorithm. We tested DCTC by simulating the impulse response of a system (hat has multiple poles and zeros near or on the unit circle and we have shown that DCTC provides a closer match to the theoretical complex eepstrum than the DFT based complex cepstrum. DCTC has been used to obtain the pitch contour of syllables, words and sentences. It is shown that the first few coefficients' spectral envelope matches with the envelope of the signal spectrum under consideration. We are also exploring the applicability of DCTC to speaker recognition.

Item Type:	Conference Paper
Publisher:	IEEE
Additional Information:	©2002 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.
Department/Centre:	Division of Electrical Sciences > Electrical Engineering
Date Deposited:	25 Aug 2008
Last Modified:	19 Sep 2010 04:13
URI:	http://eprints.iisc.ac.in/id/eprint/513

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