Does dynamic F0 increase perceived duration? New light on an old issue

This paper investigates the influence of fundamental frequency (F0) pattern on the perception of vowel duration. Three series of experiments were conducted. The first series examined dynamic vs. flat F0 contours in short vs. long vowels in German disyllabic words. The data showed that, contrary to the established opinion, a dynamic vs. a flat F0 contour shortens rather than lengthens perceived duration. This effect turned out to be independent of the character of the post-vocalic consonant, the position of the test word in the sentence and the presence or absence of a carrier phrase. The second series investigated perceived vowel duration in isolated monosyllabic words as opposed to disyllables and sentence-embedded monosyllables. The results revealed that the classical perceptual lengthening effect due to a changing F0 is only present when using isolated monosyllables. As soon as phonetically voiced stretches of speech are added, the lengthening effect is reversed. The third part dealt with the interaction of F0 and the perception of fortis/lenis plosives in disyllabic words. Here, the usual bias towards more lenis percepts due to a dynamic F0 pattern was replicated. Previous investigations explain this phenomenon by a subjectively longer vowel, mediated by a dynamic F0 contour. In view of the present results on vowel quantity perception this explanation seems no longer tenable. Instead, a production-perception link is assumed. In the light of all the present results, it must be concluded that the varying influences of F0 on the perception of duration cannot be traced back to a single, universal mechanism.