Model-based automatic evaluation of second-language learner's English segmental duration characteristics

In this paper, we propose a method of automatically measuring the segmental duration characteristics of a second-language learner's speech as a means to evaluate language proficiency in terms of speech production. We propose the use of duration differences from native speakers' speech as an objective evaluation score to evaluate the learner's English segmental duration characteristics. To provide flexible evaluation without the need to collect any additional native-English reference speech, we employed predicted normalized segmental durations using a statistical duration model instead of measured raw durations of native reference speech. The proposed evaluation method was tested using English speech data uttered by multiple Thai-native learners' groups with different amounts of experience of English study in English-as-an-o.cial- language countries. An evaluation experiment showed that the proposed measure based on duration differences is strongly correlated with the amount of English study. Moreover, segmental duration differences revealed Thai learners' speech-control characteristics such as stress assignment on word-.nal syllables. These results support the effectiveness of the proposed model-based objective evaluation.