Characterizing rhythm differences between strong and weak accented L2 speech

This study examined the rhythmic characteristics of accented L2 speech by using two relatively novel measures of prosodic rhythm: The S-AMPH measure, an index of the degree of synchrony between the stress and syllable amplitude modulation rates; and the Allan Factor measure, that determines the nested clustering of temporal events (in this case peaks in the amplitude envelope) over different timescales. An extreme-group design was used to select strong versus weak foreign accent recordings from a group of Korean and French L2 English talkers saying the same 69-word English passage. For the Korean talkers, both the S-AMPH and the Allan Factor measures differed as a function of the strength of foreign accent. This was not the case for the French talkers, where neither measure differed as a function of foreign accent strength. The difference in outcome between the Korean and French talkers suggests that the measures are not indexing some general property of L2 accent (e.g., production fluency) but rather that picking up some property specific to the strongly accented Korean talkers. We consider several options.