Noise-robust speech feature processing with empirical mode decomposition

In this article, a novel technique based on the empirical mode decomposition methodology for processing speech features is proposed and investigated. The empirical mode decomposition generalizes the Fourier analysis. It decomposes a signal as the sum of intrinsic mode functions. In this study, we implement an iterative algorithm to find the intrinsic mode functions for any given signal. We design a novel speech feature post-processing method based on the extracted intrinsic mode functions to achieve noise-robustness for automatic speech recognition. Evaluation results on the noisy-digit Aurora 2.0 database show that our method leads to significant performance improvement. The relative improvement over the baseline features increases from 24.0 to 41.1% when the proposed post-processing method is applied on mean-variance normalized speech features. The proposed method also improves over the performance achieved by a very noise-robust frontend when the test speech data are highly mismatched.