A Comparison Study on the Alignment of Prosodic and Semantic Units and Its Effects on F0 Shifting in L1 and L2 English Spontaneous Speech

Linguistic work on speech planning has established that advanced planning involves both the complexity of the subsequent utterance (i.e., utterance length) and the semantic completeness of the upcoming speech (e.g., whether the whole utterance reaches the termination of semantic units). Yet relatively little attention has been paid to the preplanning capacity of second-language (L2) learners. This study investigates whether learners are capable of pitch-related preplanning based on semantic units in discourse (DUs) in L2 spontaneous speech production. We analyzed relationships between f0 metrics and the semantic completeness of prosodic units (PUs) in English spontaneous speech by native speakers and EFL learners of Mandarin and Cantonese. The results indicate that PU-DU left alignment introduces an initial f0 up-shifting, and PU-DU right alignment produces a final f0 down-shifting in both L1 and L2 speech, suggesting speakers' sensitivity to the initiation and termination of DUs. Critically, only in L1 speech the initial f0 height correlates with PU-DU right alignment, the final f0 is connected to the left alignment, and the f0 slope is strongly related to PU-DU left and right alignment conditions. The absence of correlation in L2 speech might reflect learners' limited capacity of preplanning a whole DU in spontaneous speech production.