A Statistical Method of Evaluating Pronunciation Proficiency for English Words Spoken by Japanese

Seiichi NAKAGAWA  Naoki NAKAMURA  Kazumasa MORI  

IEICE TRANSACTIONS on Information and Systems   Vol.E87-D   No.7   pp.1917-1922
Publication Date: 2004/07/01
Online ISSN: 
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Speech and Hearing
CALL,  evaluation of pronunciation proficiency,  English learning,  speech recognition,  

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In this paper, we propose a statistical method of evaluating the pronunciation proficiency of English words spoken by Japanese. We analyzed statistically the utterances to note a combination that has a high correlation between an English teacher's score and certain acoustic features. We obserbed that the phoneme recognition rates (correct rate and accuracy) were the best measure of pronunciation proficiency, and the likelihood ratio of English phoneme acoustic models to phoneme acoustic models adapted by Japanese was the second best measure. The effective measure which was highly correlated with the English teacher's score was the combination of the likelihood for American native models, likelihood for English models adapted by Japanese, the best likelihood for arbitrary sequences of acoustic models, phoneme recognition rate and the rate of speech. We obtained a correlation coefficient of 0.81 with an open data for vocabulary and 0.69 with open data for speaker at the five words set level, respectively. The coefficient was higher than the correlation between humans' scores, 0.65. In the 15 words set level which corresponds to one or two sentences, we obtained the correlation coefficient of 0.86 with open data for the speaker.