Classification of Interrogatives as Information-Seeking or Rhetorical Questions

Rhetorical questions (RQs) differ from information-seeking questions (ISQs) in that they do not require an answer and instead seek commitment of the addressee regarding the underlying proposition. We tested the prosodic differences between ISQs and RQs in German and showed that polar RQs were mainly realized with a high plateau (H-% in the GToBI system) and polar ISQs with a high-rise (H-^H%). Wh-RQs almost exclusively ended in a low edge tone whereas wh-ISQs showed more tonal variation (L-%, L-H%, H-^H%). Irrespective of question type, RQs were mainly produced with L*+H accents. Phonetically, RQs were – compared to ISQs – more often realized with breathy voice quality in the beginning of the utterance and with longer constituent durations. The object noun was particularly lengthened. Classification and regression trees showed that polar questions can be classified on the basis of the boundary tone alone, and wh-questions by an interaction between phonological events and duration. We discuss the findings with respect to the phonology-semantics interface.publishe