Fundamental frequency patterns during spontaneous picture description.

This study was conducted to determine if fundamental voice frequency (F0) decreases throughout the course of spontaneously produced sentences, and if so, to compare the declination pattern associated with spontaneously produced sentences to the declination pattern which is reliably found when speakers read isolated sentences aloud. A picture description task was used to elicit original sentences of the speakers' own formulation while still providing considerable experimental control over the semantic content and syntactic structure of the sentences. Five speakers each formulated and produced five sentences in the picture description task and read aloud five matched sentences. F0 declination reliably occurred in one- and two-clause sentences in spontaneous speech and oral reading. There were no differences between the declination slopes in the two speech modes. We concluded that the domain of F0 declination is not strictly limited to read speech. Comparison of these findings with other recent reports suggests that declination is characteristic of sentences spoken in isolation but not of lengthy passages, independent of whether the speaker is reading aloud or speaking spontaneously.