Speaker Adaptive Training using Deep Neural Networks

Among many speaker adaptation embodiments, Speaker Adaptive Training (SAT) has been successfully applied to a standard Hidden-Markov-Model (HMM) speech recognizer, whose state is associated with Gaussian Mixture Models (GMMs). On the other hand, recent studies on Speaker-Independent (SI) recognizer development have reported that a new type of HMM speech recognizer, which replaces GMMs with Deep Neural Networks (DNNs), outperforms GMM-HMM recognizers. Along these two lines, it is natural to conceive of further improvement to a preset DNN-HMM recognizer by employing SAT. In this paper, we propose a novel training scheme that applies SAT to a SI DNN-HMM recognizer. We then implement the SAT scheme by allocating a Speaker-Dependent (SD) module to one of the intermediate layers of a seven-layer DNN, and elaborate its utility over TED Talks corpus data. Experiment results show that our speaker-adapted SAT-based DNN-HMM recognizer reduces the word error rate by 8.4% more than that of a baseline SI DNN-HMM recognizer, and (regardless of the SD module allocation) outperforms the conventional speaker adaptation scheme. The results also show that the inner layers of DNN are more suitable for the SD module than the outer layers.