Effects of temporal correction on intelligibility of foreign-accented English

Abstract

This study investigates the contribution of the temporal patterning of speech to the reduced intelligibility of foreign-accented utterances. Short English phrases spoken by a native Chinese speaker were instrumentally modified, using LPC resynthesis and dynamic time warping, so as to align the duration of acoustic segments with tokens of the same phrases spoken by a native English speaker, while retaining the spectral and source characteristics of the Chinese speaker. Similarly, the native speaker’s productions were distorted to match the durational patterns of the non-native speaker. Intelligibility of these stimuli was measured, based on native English listeners’ performance in a forced-choice identification test with four alternatives: the correct phrase plus three phonetically similar distractor phrases suggested by listening to the Chinese productions. Intelligibility of the unmodified Chinese-accented phrases was poor (39% correct), but improved significantly (to 58%) after temporal correction. Performance on the native productions was high (94%), but declined significantly (to 83%) after temporal distortion according to the Chinese speaker’s timing. These results suggest that intelligibility of foreign-language speakers may be enhanced if explicit training is provided on temporal properties of their speech.