Non-native durational patterns decrease speech intelligibility

In native speech, durational patterns convey linguistically relevant phenomena such as phrase structure, lexical stress, rhythm, and word boundaries. The lower intelligibility of non-native speech may be partly due to its deviant durational patterns. The present study aims to quantify the relative contributions of non-native durational patterns and of non-native speech sounds to intelligibility. In a Speech Reception Threshold study, duration patterns were transplanted between native and non-native versions of Dutch sentences. Intelligibility thresholds (critical speech-to-noise ratios) differed by about 4 dB between the matching versions with unchanged durational patterns. Results for manipulated versions suggest that about 0.4-1.1 dB of this difference was due to the durational patterns, and that this contribution was larger if the native and non-native patterns were more deviant. The remainder of the difference must have been due to non-native speech sounds in these materials. This finding supports recommendations to attend to durational patterns as well as native-like speech sounds, when learning to speak a foreign language. (C) 2010 Elsevier B.V. All rights reserved.