Tree-Structured Clustering Methods for Piecewise Linear-Transformation-Based Noise Adaptation

Zhipeng ZHANG
Toshiaki SUGIMURA
Sadaoki FURUI

Publication
IEICE TRANSACTIONS on Information and Systems   Vol.E88-D    No.9    pp.2168-2176
Publication Date: 2005/09/01
Online ISSN: 
DOI: 10.1093/ietisy/e88-d.9.2168
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Speech and Hearing
Keyword: 
robust speech recognition,  noise adaptation,  piecewise-linear transformation,  tree-structured noise clustering,  GMM,  

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Summary: 
This paper proposes the application of tree-structured clustering to the processing of noisy speech collected under various SNR conditions in the framework of piecewise-linear transformation (PLT)-based HMM adaptation for noisy speech. Three kinds of clustering methods are described: a one-step clustering method that integrates noise and SNR conditions and two two-step clustering methods that construct trees for each SNR condition. According to the clustering results, a noisy speech HMM is made for each node of the tree structure. Based on the likelihood maximization criterion, the HMM that best matches the input speech is selected by tracing the tree from top to bottom, and the selected HMM is further adapted by linear transformation. The proposed methods are evaluated by applying them to a Japanese dialogue recognition system. The results confirm that the proposed methods are effective in recognizing digitally noise-added speech and actual noisy speech issued by a wide range of speakers under various noise conditions. The results also indicate that the one-step clustering method gives better performance than the two-step clustering methods.


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