Improving the robustness of prosody dependent language modeling based on prosody syntax dependence
The paper presents a novel approach that improves the robustness of prosody dependent language modeling by leveraging the dependence between prosody and syntax. A prosody dependent language model describes the joint probability distribution of concurrent word and prosody sequences and can be used to provide prior language constraints in a prosody dependent speech recognizer. Robust maximum likelihood (ML) estimation of prosody dependent n-gram language models requires a large amount of prosodically transcribed data. We show that prosody-syntax dependence can be utilized to diminish the data sparseness introduced by prosody dependent modeling. Experiments on a radio news corpus show that the prosody dependent language model estimated using our approach reduces the joint perplexity by up to 34% as compared with the standard ML-estimated prosody dependent language model; the word perplexity can be reduced by up to 84% as compared with the standard ML-estimated prosody independent language model. In recognition experiments, the language model estimated by our approach create an improvement of 1% in word recognition accuracy, 0.7% in accent recognition accuracy and 1.5% in intonational phrase boundary (IPB) recognition accuracy over a baseline prosody dependent language model.