STUDY OF TEMPORAL FEATURES AND FREQUENCY-CHARACTERISTICS IN AMERICAN ENGLISH FOREIGN ACCENT

In this paper, a detailed acoustic study of foreign accent is proposed using temporal features. intonation patterns. and frequency character istics in American English. Using a database which consists of words u ttered in isolation, temporal features such as voice onset time, word- final stop closure duration, and characteristics of duration are inves tigated, Accent differences for native-produced versus Mandarin, Germa n, and Turkish accented English utterances are analyzed. Of the dimens ions considered, the most important accent relayer is found to be word -final stop closure duration. Mandarin accented English utterances sho w significant differences in terms of this feature when compared to na tive speaker utterances. In addition, the intonation characteristics a cross a set of foreign accents in American English is investigated. It is shown that Mandarin speaker utterances possess a larger negative c ontinuative intonation slope than native speaker utterances, and Germa n speaker utterances had a more positive intonation slope M-hen compar ed to native speaker utterances. Finally, a detailed frequency, analys is of foreign accented speech is conducted. It is shown that the midfr equency range (1500-2500 Hz) is the mor sensitive frequency band to no n-native speaker pronunciation variations, Based on this knowledge a n ew frequency scale for the calculation of cepstrum coefficients is for mulated which is shown to outperform the Mel-scale in terms of its abi lity to classify accent automatically among four accent classes. (C) 1 997 Acoustical Society of America.