The perception of intonational peaks and valleys: The effects of plateaux, declination and experimental task

An experiment assessed listeners’ judgement of either relative pitch height or prominence between two consecutive fundamental frequency (f_o) peaks or valleys in speech. The f_o contour of the first peak or valley was kept constant, while the second was orthogonally manipulated in its height and plateau duration. Half of the stimuli had a flat baseline from which the peaks and valleys were scaled, while the other half had an overtly declining baseline. The results replicated the previous finding that f_o peaks with a long plateau are salient to listeners, while valleys are hard to process even with a plateau. Furthermore, the effect of declination was dependent on the experimental task. Listeners’ responses seemed to be directly affected by the f_o excursion size only for judging relative height between two peaks, while their prominence judgement was strongly affected by the overall impression of the pitch raising or lowering event near the perceptual target. The findings suggest that the global f_o contour, not a single representative f_o value of an intonational event, should be considered in perceptual models of intonation. The findings show an interplay between the signal, listeners’ top-down expectations, and speech perception.