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 characteristics in American English. Using a database which consists of words uttered in isolation, temporal features such as voice onset time, word-final stop closure duration, and characteristics of duration are investigated, Accent differences for native-produced versus Mandarin, German, and Turkish accented English utterances are analyzed. Of the dimensions considered, the most important accent relayer is found to be word-final stop closure duration. Mandarin accented English utterances show significant differences in terms of this feature when compared to native speaker utterances. In addition, the intonation characteristics across a set of foreign accents in American English is investigated. It is shown that Mandarin speaker utterances possess a larger negative continuative intonation slope than native speaker utterances, and German speaker utterances had a more positive intonation slope M-hen compared to native speaker utterances. Finally, a detailed frequency, analysis of foreign accented speech is conducted. It is shown that the midfrequency range (1500-2500 Hz) is the mor sensitive frequency band to non-native speaker pronunciation variations, Based on this knowledge a new frequency scale for the calculation of cepstrum coefficients is formulated which is shown to outperform the Mel-scale in terms of its ability to classify accent automatically among four accent classes. (C) 1997 Acoustical Society of America.