Automatic speech recognition of Cantonese-English code-mixing utterances.

Chan Yeuk Chi Joyce.Thesis (M.Phil.)--Chinese University of Hong Kong, 2005.Includes bibliographical references.Abstracts in English and Chinese.Chapter Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Background --- p.1Chapter 1.2 --- Previous Work on Code-switching Speech Recognition --- p.2Chapter 1.2.1 --- Keyword Spotting Approach --- p.3Chapter 1.2.2 --- Translation Approach --- p.4Chapter 1.2.3 --- Language Boundary Detection --- p.6Chapter 1.3 --- Motivations of Our Work --- p.7Chapter 1.4 --- Methodology --- p.8Chapter 1.5 --- Thesis Outline --- p.10Chapter 1.6 --- References --- p.11Chapter Chapter 2 --- Fundamentals of Large Vocabulary Continuous Speech Recognition for Cantonese and English --- p.14Chapter 2.1 --- Basic Theory of Speech Recognition --- p.14Chapter 2.1.1 --- Feature Extraction --- p.14Chapter 2.1.2 --- Maximum a Posteriori (MAP) Probability --- p.15Chapter 2.1.3 --- Hidden Markov Model (HMM) --- p.16Chapter 2.1.4 --- Statistical Language Modeling --- p.17Chapter 2.1.5 --- Search A lgorithm --- p.18Chapter 2.2 --- Word Posterior Probability (WPP) --- p.19Chapter 2.3 --- Generalized Word Posterior Probability (GWPP) --- p.23Chapter 2.4 --- Characteristics of Cantonese --- p.24Chapter 2.4.1 --- Cantonese Phonology --- p.24Chapter 2.4.2 --- Variation and Change in Pronunciation --- p.27Chapter 2.4.3 --- Syllables and Characters in Cantonese --- p.28Chapter 2.4.4 --- Spoken Cantonese vs. Written Chinese --- p.28Chapter 2.5 --- Characteristics of English --- p.30Chapter 2.5.1 --- English Phonology --- p.30Chapter 2.5.2 --- English with Cantonese Accents --- p.31Chapter 2.6 --- References --- p.32Chapter Chapter 3 --- Code-mixing and Code-switching Speech Recognition --- p.35Chapter 3.1 --- Introduction --- p.35Chapter 3.2 --- Definition --- p.35Chapter 3.2.1 --- Monolingual Speech Recognition --- p.35Chapter 3.2.2 --- Multilingual Speech Recognition --- p.35Chapter 3.2.3 --- Code-mixing and Code-switching --- p.36Chapter 3.3 --- Conversation in Hong Kong --- p.38Chapter 3.3.1 --- Language Choice of Hong Kong People --- p.38Chapter 3.3.2 --- Reasons for Code-mixing in Hong Kong --- p.40Chapter 3.3.3 --- How Does Code-mixing Occur? --- p.41Chapter 3.4 --- Difficulties for Code-mixing - Specific to Cantonese-English --- p.44Chapter 3.4.1 --- Phonetic Differences --- p.45Chapter 3.4.2 --- Phonology difference --- p.48Chapter 3.4.3 --- Accent and Borrowing --- p.49Chapter 3.4.4 --- Lexicon and Grammar --- p.49Chapter 3.4.5 --- Lack of Appropriate Speech Corpus --- p.50Chapter 3.5 --- References --- p.50Chapter Chapter 4 --- Data Collection --- p.53Chapter 4.1 --- Data Collection --- p.53Chapter 4.1.1 --- Corpus Design --- p.53Chapter 4.1.2 --- Recording Setup --- p.59Chapter 4.1.3 --- Post-processing of Speech Data --- p.60Chapter 4.2 --- A Baseline Database --- p.61Chapter 4.2.1 --- Monolingual Spoken Cantonese Speech Data (CUMIX) --- p.61Chapter 4.3 --- References --- p.61Chapter Chapter 5 --- System Design and Experimental Setup --- p.63Chapter 5.1 --- Overview of the Code-mixing Speech Recognizer --- p.63Chapter 5.1.1 --- Bilingual Syllable / Word-based Speech Recognizer --- p.63Chapter 5.1.2 --- Language Boundary Detection --- p.64Chapter 5.1.3 --- Generalized Word Posterior Probability (GWPP) --- p.65Chapter 5.2 --- Acoustic Modeling --- p.66Chapter 5.2.1 --- Speech Corpus for Training of Acoustic Models --- p.67Chapter 5.2.2 --- Features Extraction --- p.69Chapter 5.2.3 --- Variability in the Speech Signal --- p.69Chapter 5.2.4 --- Language Dependency of the Acoustic Models --- p.71Chapter 5.2.5 --- Pronunciation Dictionary --- p.80Chapter 5.2.6 --- The Training Process of Acoustic Models --- p.83Chapter 5.2.7 --- Decoding and Evaluation --- p.88Chapter 5.3 --- Language Modeling --- p.90Chapter 5.3.1 --- N-gram Language Model --- p.91Chapter 5.3.2 --- Difficulties in Data Collection --- p.91Chapter 5.3.3 --- Text Data for Training Language Model --- p.92Chapter 5.3.4 --- Training Tools --- p.95Chapter 5.3.5 --- Training Procedure --- p.95Chapter 5.3.6 --- Evaluation of the Language Models --- p.98Chapter 5.4 --- Language Boundary Detection --- p.99Chapter 5.4.1 --- Phone-based LBD --- p.100Chapter 5.4.2 --- Syllable-based LBD --- p.104Chapter 5.4.3 --- LBD Based on Syllable Lattice --- p.106Chapter 5.5 --- "Integration of the Acoustic Model Scores, Language Model Scores and Language Boundary Information" --- p.107Chapter 5.5.1 --- Integration of Acoustic Model Scores and Language Boundary Information. --- p.107Chapter 5.5.2 --- Integration of Modified Acoustic Model Scores and Language Model Scores --- p.109Chapter 5.5.3 --- Evaluation Criterion --- p.111Chapter 5.6 --- References --- p.112Chapter Chapter 6 --- Results and Analysis --- p.118Chapter 6.1 --- Speech Data for Development and Evaluation --- p.118Chapter 6.1.1 --- Development Data --- p.118Chapter 6.1.2 --- Testing Data --- p.118Chapter 6.2 --- Performance of Different Acoustic Units --- p.119Chapter 6.2.1 --- Analysis of Results --- p.120Chapter 6.3 --- Language Boundary Detection --- p.122Chapter 6.3.1 --- Phone-based Language Boundary Detection --- p.123Chapter 6.3.2 --- Syllable-based Language Boundary Detection (SYL LB) --- p.127Chapter 6.3.3 --- Language Boundary Detection Based on Syllable Lattice (BILINGUAL LBD) --- p.129Chapter 6.3.4 --- Observations --- p.129Chapter 6.4 --- Evaluation of the Language Models --- p.130Chapter 6.4.1 --- Character Perplexity --- p.130Chapter 6.4.2 --- Phonetic-to-text Conversion Rate --- p.131Chapter 6.4.3 --- Observations --- p.131Chapter 6.5 --- Character Error Rate --- p.132Chapter 6.5.1 --- Without Language Boundary Information --- p.133Chapter 6.5.2 --- With Language Boundary Detector SYL LBD --- p.134Chapter 6.5.3 --- With Language Boundary Detector BILINGUAL-LBD --- p.136Chapter 6.5.4 --- Observations --- p.138Chapter 6.6 --- References --- p.141Chapter Chapter 7 --- Conclusions and Suggestions for Future Work --- p.143Chapter 7.1 --- Conclusion --- p.143Chapter 7.1.1 --- Difficulties and Solutions --- p.144Chapter 7.2 --- Suggestions for Future Work --- p.149Chapter 7.2.1 --- Acoustic Modeling --- p.149Chapter 7.2.2 --- Pronunciation Modeling --- p.149Chapter 7.2.3 --- Language Modeling --- p.150Chapter 7.2.4 --- Speech Data --- p.150Chapter 7.2.5 --- Language Boundary Detection --- p.151Chapter 7.3 --- References --- p.151Appendix A Code-mixing Utterances in Training Set of CUMIX --- p.152Appendix B Code-mixing Utterances in Testing Set of CUMIX --- p.175Appendix C Usage of Speech Data in CUMIX --- p.20

Language modeling for speech recognition of spoken Cantonese.

Yeung, Yu Ting.Thesis (M.Phil.)--Chinese University of Hong Kong, 2009.Includes bibliographical references (leaves 84-93).Abstracts in English and Chinese.Acknowledgement --- p.iiiAbstract --- p.ivChapter 1 --- Introduction --- p.1Chapter 1.1 --- Cantonese Speech Recognition --- p.3Chapter 1.2 --- Objectives --- p.4Chapter 1.3 --- Thesis Outline --- p.5Chapter 2 --- Fundamentals of Large Vocabulary Continuous Speech Recognition --- p.7Chapter 2.1 --- Problem Formulation --- p.7Chapter 2.2 --- Feature Extraction --- p.8Chapter 2.3 --- Acoustic Models --- p.9Chapter 2.4 --- Decoding --- p.10Chapter 2.5 --- Statistical Language Modeling --- p.12Chapter 2.5.1 --- N-gram Language Models --- p.12Chapter 2.5.2 --- N-gram Smoothing --- p.13Chapter 2.5.3 --- Complexity of Language Model --- p.15Chapter 2.5.4 --- Class-based Langauge Model --- p.16Chapter 2.5.5 --- Language Model Pruning --- p.17Chapter 2.6 --- Performance Evaluation --- p.18Chapter 3 --- The Cantonese Dialect --- p.19Chapter 3.1 --- Phonology of Cantonese --- p.19Chapter 3.2 --- Orthographic Representation of Cantonese --- p.22Chapter 3.3 --- Classification of Cantonese speech --- p.25Chapter 3.4 --- Cantonese-English Code-mixing --- p.27Chapter 4 --- Rule-based Translation Method --- p.29Chapter 4.1 --- Motivations --- p.29Chapter 4.2 --- Transformation-based Learning --- p.30Chapter 4.2.1 --- Algorithm Overview --- p.30Chapter 4.2.2 --- Learning of Translation Rules --- p.32Chapter 4.3 --- Performance Evaluation --- p.35Chapter 4.3.1 --- The Learnt Translation Rules --- p.35Chapter 4.3.2 --- Evaluation of the Rules --- p.37Chapter 4.3.3 --- Analysis of the Rules --- p.37Chapter 4.4 --- Preparation of Training Data for Language Modeling --- p.41Chapter 4.5 --- Discussion --- p.43Chapter 5 --- Language Modeling for Cantonese --- p.44Chapter 5.1 --- Training Data --- p.44Chapter 5.1.1 --- Text Corpora --- p.44Chapter 5.1.2 --- Preparation of Formal Cantonese Text Data --- p.45Chapter 5.2 --- Training of Language Models --- p.46Chapter 5.2.1 --- Language Models for Standard Chinese --- p.46Chapter 5.2.2 --- Language Models for Formal Cantonese --- p.46Chapter 5.2.3 --- Language models for Colloquial Cantonese --- p.47Chapter 5.3 --- Evaluation of Language Models --- p.48Chapter 5.3.1 --- Speech Corpora for Evaluation --- p.48Chapter 5.3.2 --- Perplexities of Formal Cantonese Language Models --- p.49Chapter 5.3.3 --- Perplexities of Colloquial Cantonese Language Models --- p.51Chapter 5.4 --- Speech Recognition Experiments --- p.53Chapter 5.4.1 --- Speech Corpora --- p.53Chapter 5.4.2 --- Experimental Setup --- p.54Chapter 5.4.3 --- Results on Formal Cantonese Models --- p.55Chapter 5.4.4 --- Results on Colloquial Cantonese Models --- p.56Chapter 5.5 --- Analysis of Results --- p.58Chapter 5.6 --- Discussion --- p.59Chapter 5.6.1 --- Cantonese Language Modeling --- p.59Chapter 5.6.2 --- Interpolated Language Models --- p.59Chapter 5.6.3 --- Class-based Language Models --- p.60Chapter 6 --- Towards Language Modeling of Code-mixing Speech --- p.61Chapter 6.1 --- Data Collection --- p.61Chapter 6.1.1 --- Data Collection --- p.62Chapter 6.1.2 --- Filtering of Collected Data --- p.63Chapter 6.1.3 --- Processing of Collected Data --- p.63Chapter 6.2 --- Clustering of Chinese and English Words --- p.64Chapter 6.3 --- Language Modeling for Code-mixing Speech --- p.64Chapter 6.3.1 --- Language Models from Collected Data --- p.64Chapter 6.3.2 --- Class-based Language Models --- p.66Chapter 6.3.3 --- Performance Evaluation of Code-mixing Language Models --- p.67Chapter 6.4 --- Speech Recognition Experiments with Code-mixing Language Models --- p.69Chapter 6.4.1 --- Experimental Setup --- p.69Chapter 6.4.2 --- Monolingual Cantonese Recognition --- p.70Chapter 6.4.3 --- Code-mixing Speech Recognition --- p.72Chapter 6.5 --- Discussion --- p.74Chapter 6.5.1 --- Data Collection from the Internet --- p.74Chapter 6.5.2 --- Speech Recognition of Code-mixing Speech --- p.75Chapter 7 --- Conclusions and Future Work --- p.77Chapter 7.1 --- Conclusions --- p.77Chapter 7.1.1 --- Rule-based Translation Method --- p.77Chapter 7.1.2 --- Cantonese Language Modeling --- p.78Chapter 7.1.3 --- Code-mixing Language Modeling --- p.78Chapter 7.2 --- Future Works --- p.79Chapter 7.2.1 --- Rule-based Translation --- p.79Chapter 7.2.2 --- Training data --- p.80Chapter 7.2.3 --- Code-mixing speech --- p.80Chapter A --- Equation Derivation --- p.82Chapter A.l --- Relationship between Average Mutual Information and Perplexity --- p.82Bibliography --- p.8

Code-Switching without Switching: Language Agnostic End-to-End Speech Translation

We propose a) a Language Agnostic end-to-end Speech Translation model (LAST), and b) a data augmentation strategy to increase code-switching (CS) performance. With increasing globalization, multiple languages are increasingly used interchangeably during fluent speech. Such CS complicates traditional speech recognition and translation, as we must recognize which language was spoken first and then apply a language-dependent recognizer and subsequent translation component to generate the desired target language output. Such a pipeline introduces latency and errors. In this paper, we eliminate the need for that, by treating speech recognition and translation as one unified end-to-end speech translation problem. By training LAST with both input languages, we decode speech into one target language, regardless of the input language. LAST delivers comparable recognition and speech translation accuracy in monolingual usage, while reducing latency and error rate considerably when CS is observed

Pronunciation Modeling of Foreign Words for Mandarin ASR by Considering the Effect of Language Transfer

One of the challenges in automatic speech recognition is foreign words recognition. It is observed that a speaker's pronunciation of a foreign word is influenced by his native language knowledge, and such phenomenon is known as the effect of language transfer. This paper focuses on examining the phonetic effect of language transfer in automatic speech recognition. A set of lexical rules is proposed to convert an English word into Mandarin phonetic representation. In this way, a Mandarin lexicon can be augmented by including English words. Hence, the Mandarin ASR system becomes capable to recognize English words without retraining or re-estimation of the acoustic model parameters. Using the lexicon that derived from the proposed rules, the ASR performance of Mandarin English mixed speech is improved without harming the accuracy of Mandarin only speech. The proposed lexical rules are generalized and they can be directly applied to unseen English words.Comment: Published by INTERSPEECH 201

Introducing Phonetic Information to Speaker Embedding for Speaker Verification

Phonetic information is one of the most essential components of a speech signal, playing an important role for many speech processing tasks. However, it is difficult to integrate phonetic information into speaker verification systems since it occurs primarily at the frame level while speaker characteristics typically reside at the segment level. In deep neural network-based speaker verification, existing methods only apply phonetic information to the frame-wise trained speaker embeddings. To improve this weakness, this paper proposes phonetic adaptation and hybrid multi-task learning and further combines these into c-vector and simplified c-vector architectures. Experiments on National Institute of Standards and Technology (NIST) speaker recognition evaluation (SRE) 2010 show that the four proposed speaker embeddings achieve better performance than the baseline. The c-vector system performs the best, providing over 30% and 15% relative improvements in equal error rate (EER) for the core-extended and 10 s–10 s conditions, respectively. On the NIST SRE 2016, 2018, and VoxCeleb datasets, the proposed c-vector approach improves the performance even when there is a language mismatch within the training sets or between the training and evaluation sets. Extensive experimental results demonstrate the effectiveness and robustness of the proposed methods

Identification of Code-Switched Sentences and Words Using Language Modeling Approaches

Globalization and multilingualism contribute to code-switching—the phenomenon in which speakers produce utterances containing words or expressions from a second language. Processing code-switched sentences is a significant challenge for multilingual intelligent systems. This study proposes a language modeling approach to the problem of code-switching language processing, dividing the problem into two subtasks: the detection of code-switched sentences and the identification of code-switched words in sentences. A code-switched sentence is detected on the basis of whether it contains words or phrases from another language. Once the code-switched sentences are identified, the positions of the code-switched words in the sentences are then identified. Experimental results show that the language modeling approach achieved an F-measure of 80.43% and an accuracy of 79.01% for detecting Mandarin-Taiwanese code-switched sentences. For the identification of code-switched words, the word-based and POS-based models, respectively, achieved F-measures of 41.09% and 53.08%