Iambic-Trochaic grouping in native listeners of Papuan Malay, Akan, and German.

Grouping helps listeners to break down the speech signal into smaller units. Specific acoustic cues, in particular duration and intensity, have been reported to determine grouping of disyllabic units across languages [Iambic-Trochaic Law (ITL)]. The ITL states that iambic grouping is obtained from syllabic sequences alternating in duration, whereas trochaic grouping is obtained from those alternating in intensity. Speakers of different languages vary in the extent to which they use the ITL. It has been proposed that this linguistic modulation of the ITL relates to cross-linguistic differences in prosody. The present study further investigates the predictions of the ITL in two under-researched languages, Papuan Malay and Akan, for which there is controversy on the existence of word stress. They are compared to German, a well-researched language with variable word stress. A perceptual grouping task used in previous work is replicated with listeners from each language. The results show considerable cross-linguistic differences and shed light on acoustic perceptual properties in Papuan Malay and Akan. The outcomes reconfirm cross-linguistic variability and modulation of the applicability of the ITL across languages.