Unsupervised model adaptation for continuous speech recognition using model-level confidence measures.

Kwan Ka Yan.Thesis (M.Phil.)--Chinese University of Hong Kong, 2002.Includes bibliographical references.Abstracts in English and Chinese.Chapter 1. --- Introduction --- p.1Chapter 1.1. --- Automatic Speech Recognition --- p.1Chapter 1.2. --- Robustness of ASR Systems --- p.3Chapter 1.3. --- Model Adaptation for Robust ASR --- p.4Chapter 1.4. --- Thesis outline --- p.6References --- p.8Chapter 2. --- Fundamentals of Continuous Speech Recognition --- p.10Chapter 2.1. --- Acoustic Front-End --- p.10Chapter 2.2. --- Recognition Module --- p.11Chapter 2.2.1. --- Acoustic Modeling with HMM --- p.12Chapter 2.2.2. --- Basic Phonology of Cantonese --- p.14Chapter 2.2.3. --- Acoustic Modeling for Cantonese --- p.15Chapter 2.2.4. --- Language Modeling --- p.16References --- p.17Chapter 3. --- Unsupervised Model Adaptation --- p.18Chapter 3.1. --- A General Review of Model Adaptation --- p.18Chapter 3.1.1. --- Supervised and Unsupervised Adaptation --- p.20Chapter 3.1.2. --- N-Best Adaptation --- p.22Chapter 3.2. --- MAP --- p.23Chapter 3.3. --- MLLR --- p.25Chapter 3.3.1. --- Adaptation Approach --- p.26Chapter 3.3.2. --- Estimation of MLLR regression matrices --- p.27Chapter 3.3.3. --- Least Mean Squares Regression --- p.29Chapter 3.3.4. --- Number of Transformations --- p.30Chapter 3.4. --- Experiment Results --- p.32Chapter 3.4.1. --- Standard MLLR versus LMS MLLR --- p.36Chapter 3.4.2. --- Effect of the Number of Transformations --- p.43Chapter 3.4.3. --- MAP Vs. MLLR --- p.46Chapter 3.5. --- Conclusions --- p.48ReferencesxlixChapter 4. --- Use of Confidence Measure for MLLR based Adaptation --- p.50Chapter 4.1. --- Introduction to Confidence Measure --- p.50Chapter 4.2. --- Confidence Measure Based on Word Density --- p.51Chapter 4.3. --- Model-level confidence measure --- p.53Chapter 4.4. --- Integrating Confusion Information into Confidence Measure --- p.55Chapter 4.5. --- Adaptation Data Distributions in Different Confidence Measures..… --- p.57References --- p.65Chapter 5. --- Experimental Results and Analysis --- p.66Chapter 5.1. --- Supervised Adaptation --- p.67Chapter 5.2. --- Cheated Confidence Measure --- p.69Chapter 5.3. --- Confidence Measures of Different Levels --- p.71Chapter 5.4. --- Incorporation of Confusion Matrix --- p.81Chapter 5.5. --- Conclusions --- p.83Chapter 6. --- Conclusions --- p.35Chapter 6.1. --- Future Works --- p.8