Metrical enhancement in American English nuclear tunes

We present two experiments aimed at testing the nature of intonational categories through the lens of enhancement. In an imitative speech production paradigm, speakers heard a model intonational tune and were prompted to reproduce that tune on a new sentence in which the syllable count of the word carrying the tune varied. Using the prevalent auto-segmental metrical model of American English as a basis for potential tune categories, we test how distinctions among tunes are enhanced across different metrical structures. First, with a clustering analysis, we find that not all predicted distinctions are emergent. Secondly, only the largest distinctions, those that emerge in the clustering analysis, are enhanced as a function of metrical structure. Measurable differences between tunes which cluster together are detectable, but critically, are not enhanced. We discuss what these results mean for the nature and number of intonational categories in the system