Environmental robustness for automatic speech recognition systems based on parameter modification can be accomplished in two complementary ways. One approach is to modify the incoming features of environmentally-degra...
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Environmental robustness for automatic speech recognition systems based on parameter modification can be accomplished in two complementary ways. One approach is to modify the incoming features of environmentally-degraded speech to more closely resemble the features of the (normally undegraded) speech used to train the classifier. The other approach is to modifying the internal statistical representations of speech features used by the classifier to more closely resemble the features representing degraded speech in a particular target environment. This paper attempts to unify these two approaches to robust speech recognition by presenting several techniques that share the same basic assumptions and internal structure while differing in whether they modify the features of incoming speech or whether they modify the statistics of the classifier itself. We present the multivaRiate gAussian-based cepsTral normaliZation (RATZ) family of algorithms which modify incoming cepstral features, along with the STAR (STAtistical Reestimation) family of algorithms, which modify the internal statistics of the classifier. Both types of algorithms are datadriven, in that they make use of a certain amount of adaptation data for learning compensation parameters. The algorithms were evaluated using the SPHINX-II speech recognition system on subsets of the Wall Street Journal database. While all algorithms demonstrated improved recognition accuracy compared to previous algorithms, the STAR family of algorithms tended to provide lower error rates than the RATZ family of algorithms as the SNR was decreased. (C) 1998 Elsevier Science B.V. All rights reserved.
Presents the mathematical study of approaches for defining nested arrays in APL, a computer program language. Discussion on the extension of data structure capability of APL; data structure of APL; Characteristics of ...
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Presents the mathematical study of approaches for defining nested arrays in APL, a computer program language. Discussion on the extension of data structure capability of APL; data structure of APL; Characteristics of APL; Function of APL as an algorithm notation.
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