rozpoznávání řeči --- vietnamština

This thesis presents the work on automatic speech recognition of Vietnamese, a tonal, syllable-based language in which new approaches have to be applied to obtain reliable results. When dealing with Vietnamese, the following basic problems have to be solved or clarified: the selection of phonetic unit to build acoustic models, the collection of text and speech corpora, the creation of pronouncing dictionary, the construction of language model and especially, the methods to deal with tone. With the basic idea of systematically and methodically finding solutions to all the problems mention above, in this work, several methods for collecting large text and speech corpora are first described in which two types of text corpora are obtained by exploiting the source of linguistic data from the Internet, and also two types of speech corpora are extracted, including an Internet-based large continuous speech corpus and a recorded audio-visual speech corpus. Then, a standard phoneme set optimal to Vietnamese with its corresponding grapheme-to-phoneme mapping table is proposed. By constructing various types of pronunciation dictionaries and language models for Vietnamese, the optimal way to integrate tone in a syllable as well as the strategies to deal with speech recognition of Vietnamese will be totally examined in the form of large vocabulary continuous speech recognition tasks. The study is further extended to the field of audio-visual speech recognition of Vietnamese in which the performance gains of audio only speech recognition in noisy condition is proved to be noticeable when integrated with visual information. In this work, many types of visual front ends and visual features are examined in the task of isolated-word speech recognition of Vietnamese.; Práce se zabývá zpracování vietnamského jazyka. V rámci práce jsou navrženy, implementovány a otestovány algoritmy pro rozpoznávání spojité řeči s přihlédnutím na specifika vietnamského jazyka. Součástí práce je i kapitola věnovaná audiovizuálnímu rozpoznávání řeči při využití metody AM.

Automatic speech recognition of Vietnamese