7th International Conference on Spoken Language Processing

September 16-20, 2002
Denver, Colorado, USA

Quantile Based Histogram Equalization for Online Applications

Florian Hilger, Sirko Molau, Hermann Ney

RWTH Aachen - University of Technology, Germany

The noise robustness of automatic speech recognition systems can be increased by transforming the signal to make the cumulative density functions of the signalís values in recognition match the ones that where estimated on the training data. This paper describes a real-time online algorithm to approximate the cumulative density functions, after Mel scaled filtering, using a small number of quantiles. Recognition tests where carried out on the Aurora noisy TI digit strings and SpeechDat-Car databases. The average relative reduction of the word error rates was 32% on the noisy TI digit strings and 29% on SpeechDat-Car.


Full Paper

Bibliographic reference.  Hilger, Florian / Molau, Sirko / Ney, Hermann (2002): "Quantile based histogram equalization for online applications", In ICSLP-2002, 237-240.