Nouns and verbs in the speech signal: Are there phonetic correlates of grammatical category?

Abstract

AbstractOver the past decades a considerable number of works have observed differences in the phonetic realization of nouns and verbs. The guiding question in most relevant research is whether such differences are caused by grammatical category per se, or are triggered by more general processes of phonetic implementation that impact nouns and verbs differently. Most studies argue for the latter and focus on one particular process or variable, which is advocated to be responsible for the acoustic differences observed. Among the processes mentioned are pre-boundary lengthening, accentuation, and frequency-induced reduction. Due to the focus on monofactorial explanations, an overview and contextualization of the different processes interacting with the noun-verb distinction is yet missing. The present paper aims to fill this gap. This goal is pursed by providing an in-depth discussion of how grammatical category interacts with a number of different processes that affect acoustic realization. To that end results from the literature on the topic are synthesized with new acoustic analyses of noun-verb homophones from spontaneous speech. The analysis shows that differences in acoustic realization between nouns and verbs are caused by the complex interplay of a number of different processes, defying simple, monofactorial explanations.