Copyright © 2008 The Institute of Electronics, Information and Communication Engineers
Special Section on Robust Speech Processing in Realistic Environments -- Papers -- Feature Extraction |
Linear Discriminant Analysis Using a Generalized Mean of Class Covariances and Its Application to Speech Recognition
1 The author is with DENSO CORPORATION, Nisshin-shi, 470–0111 Japan. E-mail: msakai{at}rlab.denso.co.jp, 2 The authors are with Nagoya University, Nagoya-shi, 464–8603 Japan. E-mail: kitaoka{at}nagoya-u.jp, 3 The author is with Toyohashi University of Technology, Toyohashi-shi, 441–8580 Japan. E-mail: nakagawa{at}slp.ics.tut.ac.jp
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Abstract |
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To precisely model the time dependency of features is one of the important issues for speech recognition. Segmental unit input HMM with a dimensionality reduction method has been widely used to address this issue. Linear discriminant analysis (LDA) and heteroscedastic extensions, e.g., heteroscedastic linear discriminant analysis (HLDA) or heteroscedastic discriminant analysis (HDA), are popular approaches to reduce dimensionality. However, it is difficult to find one particular criterion suitable for any kind of data set in carrying out dimensionality reduction while preserving discriminative information. In this paper, we propose a new framework which we call power linear discriminant analysis (PLDA). PLDA can be used to describe various criteria including LDA, HLDA, and HDA with one control parameter. In addition, we provide an efficient selection method using a control parameter without training HMMs nor testing recognition performance on a development data set. Experimental results show that the PLDA is more effective than conventional methods for various data sets.
Key Words: speech recognition, feature extraction, multidimensional signal processing
Manuscript received July 2, 2007. Manuscript revised September 14, 2007.