This study investigates a variety of rhythm metrics on two corpora of non-native spontaneous speech and compares the non-native distributions to values from a corpus of native speech. Several of the metrics are shown to differentiate well between native and nonnative speakers and to also have moderate correlations with English proficiency scores that were assigned to the non-native speech. The metric that had the highest correlation with English proficiency scores (apart from speaking rate) was rPVIsyl (the raw Pairwise Variability Index for syllables), with r=-0.43.

Index Terms: Rhythm metrics, non-native speech, fluency