Organizing syllables into groups - Evidence from F0 and duration patterns in Mandarin

In this study we investigated grouping-related F0 patterns in Mandarin by examining the effect of syllable position in a group while controlling for tone, speaking mode, number of syllables in a group, and group position in a sentence. We analyzed syllable duration, F0 displacement, ratio of peak velocity to F0 displacement (vp/d ratio) and shape of F0 velocity profile (parameter C) in sequences of Rising, Falling and High tones. Results showed that syllable duration had the most consistent grouping-related patterns. In a short phrase of 1-4 syllables, duration is longest in the final position, second longest in the initial position, and shortest in the medial positions. In Rising and Falling tone sequences, syllable duration was positively related to F0 displacement, but negatively related to vp/d ratio. Sequences consisting of only the High tone, however, showed no duration-matching F0 variations. Modeling simulations with a second-order linear system showed that duration variations alone could generate F0 displacement and vp/d ratio variations comparable to those in actual data. We interpret the results as evidence that grouping is encoded directly by syllable duration, while the corresponding variations in F0 displacement, vp/d ratio and velocity profile are the consequences of duration control.