Fundamental Frequency and Discourse Structure

The height of clause-peak fundamental frequency (normalized across speakers) was taken as the physical correlate of an observer's global impression of the relative pitch height of utterances embedded in a natural conversation. Normalized clause-peak fundamental frequency (F o) is shown to be a reflection (and is conjectured to be a signal) of discourse structure in a sample of over 1700 clauses taken from 16 laboratory-playroom parent-child conversations. The change in this parameter from the first to the second member of pairs of successive utterances was shown to be correlated with (nearly exhaustive) classification of these pairs into 11 discourse categories. Some of these categories are well recognized (e.g., Topic Change, Back-Channel, Wh-questions and their pragmatic equivalents) and others , were developed for this study (e.g., Aspect Change, Modulation Question, Consonant, Dissonant, Disagree). Overall, the discourse correlate of an increase in normalized clause-peak F o from the first to the second member of a pair appears to be summarizable under the pragmatic rubric of "degree of disturbance in discourse flow" occasioned by the second member of the pair. These findings are expected to generalize to other conversational settings; however, we conjecture that in general the discourse information carried by pitch may sometimes be at variance with that carried by text, and propose that further work be experimental rather than observational. The relation between discourse and "affective" pitch use is examined and potential neurolinguistic applications of this research are discussed.