Histogram Equalization Utilizing Window-Based Smoothed CDF Estimation for Feature Compensation

In this letter, we propose a new histogram equalization method to compensate for acoustic mismatches mainly caused by corruption of additive noise and channel distortion in speech recognition. The proposed method employs an improved test cumulative distribution function (CDF) by more accurately smoothing the conventional order statisticsbased test CDF with the use of window functions for robust feature compensation. Experiments on the AURORA 2 framework confirmed that the proposed method is effective in compensating speech recognition features by reducing the averaged relative error by 13.12% over the order statisticsbased conventional histogram equalization method and by 58.02% over the mel-cepstral-based features for the three test sets. key words: feature compensation, histogram equalization, robust speech recognition, window-based CDF estimation