Articulatory features from deep neural networks and their role in speech recognition

This paper presents a deep neural network (DNN) to extract articulatory information from the speech signal and explores different ways to use such information in a continuous speech recognition task. The DNN was trained to estimate articulatory trajectories from input speech, where the training data is a corpus of synthetic English words generated by the Haskins Laboratories´ task-dynamic model of speech production. Speech parameterized as cepstral features were used to train the DNN, where we explored different cepstral features to observe their role in the accuracy of articulatory trajectory estimation. The best feature was used to train the final DNN system, where the system was used to predict articulatory trajectories for the training and testing set of Aurora-4, the noisy Wall Street Journal (WSJ0) corpus. This study also explored the use of hidden variables in the DNN pipeline as a potential acoustic feature candidate for speech recognition and the results were encouraging. Word recognition results from Aurora-4 indicate that the articulatory features from the DNN provide improvement in speech recognition performance when fused with other standard cepstral features; however when tried by themselves, they failed to match the baseline performance.