12th Annual Conference of the International Speech Communication Association

Florence, Italy
August 27-31. 2011

Sub-Band Level Histogram Equalization for Robust Speech Recognition

Vikas Joshi (1), Raghavendra Bilgi (1), S. Umesh (1), L. Garcia (2), C. Benitez (2)

(1) IIT Madras, India
(2) Universidad de Granada, Spain

This paper describes a novel modification of Histogram Equalization (HEQ) approach to robust speech recognition. We propose separate equalization of the high frequency (HF) and low frequency (LF) bands. We study different combinations of the sub-band equalization and obtain best results when we perform a two-stage equalization. First, conventional HEQ is performed on the cepstral features, which does not completely equalize HF and LF bands, even though the overall histogram equalization is good. In the second stage, an equalization is done separately on the HF and the LF components of the above equalized cepstra. We refer to this approach as Sub-band Histogram Equalization (S-HEQ). The new set of features has better equalization of the sub-bands as well as the overall cepstral histogram. Recognition results show a relative improvement of 12% and 15% over conventional HEQ in WER on Aurora-2 and Aurora-4 databases respectively.

Full Paper

Bibliographic reference.  Joshi, Vikas / Bilgi, Raghavendra / Umesh, S. / Garcia, L. / Benitez, C. (2011): "Sub-band level histogram equalization for robust speech recognition", In INTERSPEECH-2011, 1661-1664.