Published online by Cambridge University Press: 20 May 2014
The Iambic-Trochaic Law (ITL) asserts that listeners associate greater acoustic intensity with group beginnings and greater duration with group endings. Some researchers have assumed a natural connection between these perceptual tendencies and universal principles underlying linguistic categories of rhythm. The experimental literature on ITL effects is limited in three ways. Few studies of listeners' perceptions of alternating sound sequences have used speech-like stimuli, cross-linguistic testing has been inadequate and existing studies have manipulated intensity and duration singly, whereas these features vary together in natural speech. This paper reports the results of three experiments conducted with native Zapotec speakers and one with native English speakers. We tested listeners' grouping biases using streams of alternating syllables in which intensity and duration were varied separately, and sequences in which they were covaried. The findings suggest that care should be taken in assuming a natural connection between the ITL and universal principles of prosodic organisation.
This research was supported by National Science Foundation award 1147959 to the first author. The second author thanks the Center for the Study and Development of the Indigenous Languages of Oaxaca for release time to conduct the research. We have appreciated useful comments from Keith Johnson, Mark Liberman, Björn Lindblom, Richard Meier, Gayatri Rao, Rajka Smiljanic and Caroline Smith at various points. We are especially indebted to Colin Bannard, Randy Diehl, Matthew Gordon, Niamh Kelly, Scott Myers and four Phonology reviewers for their generous contributions to the design, statistical analysis and earlier versions of the manuscript. Finally, we thank the editors for their gracious and meticulous editing. Naturally, the responsibility for any limitations is ours alone. Portions of this research were presented at the 2013 meeting of the Society for the Study of Indigenous Languages of the Americas and at M@90, a workshop in honour of Morris Halle's 90th birthday in Cambridge, Mass. in September 2013.