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 (v_p/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 v_p/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 v_p/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, v_p/d ratio and velocity profile are the consequences of duration control.