Phonetic Effects of Tonal Crowding in Persian Polar Questions

Persian polar questions are characterized by a rise-fall followed by a low F0 plateau and a final rise. A production experiment was designed which systematically manipulated question length and the position of stress in the nuclear accented word in the question. Results revealed that distances between tones can strongly affect their scaling and alignment in predictable manner. With respect to scaling, our data show that the postnuclear low F0 target is realized considerably higher in short questions in which tonal crowding is more acute. This scaling adjustment of the L affects the following H tone, such that the final H is realized higher in tonal space, relative to the other crowding contexts. The results for duration show that in short questions, syllable duration is significantly lengthened so that there is room for tonal targets to be realized. In addition, the alignment data in this study suggest that crowding contexts incrementally affect the temporal adjustment of tonal targets. In some circumstances, tonal crowding results in anticipatory retraction of tones, while in others it results in carry-over tonal displacement depending on the direction of the prosodic pressure. These results can best be explained in an auto-segmental approach to intonational phonology in which intonation contours are treated as strings of distinct high and low tones associated with specific elements in the segmental string.