Characterizing first and second language rhythm in English using spectral coherence between temporal envelope and mouth opening-closing movements.

Abstract

This study investigated the rhythmic differences between first and second language English from 19 native speakers of American English and an equal number of native speakers of Mandarin. Speech rhythm was viewed from MacNeilage's frame/content theory. The spectral coherence between the temporal envelope and the mouth opening and closing kinematics was computed to operationalize the rhythmic frame. The spectral centroid, spread, rolloff, flatness, and entropy were calculated to reveal the frequency distribution patterns in the coherence. Using a binary logistic regression model, these measures were collectively found to be effective in characterizing rhythmic differences between native and non-native groups (A' = 0.71 and B″D = -0.06). Specifically, the native group was significantly higher than the non-native group in terms of spectral centroid and spread, whereas the native group was significantly lower than its non-native counterpart in terms of spectral flatness and entropy. Both groups were not significantly different in spectral rolloff. Possible explanations for the result as well as the efficacy of employing the aforesaid coherence in speech rhythm research in general were discussed.