An ultrasound study of ambisyllabicity: The case of American English retroflex /ɹ/

Abstract

Ambisyllabicity has long been central to phonological theory, yet its articulatory basis remains unclear. This study investigates whether American English ambisyllabic retroflex /ɹ/ exhibits intermediate tongue configurations between onset and coda realizations in spatial and/or temporal dimensions. Ultrasound imaging data were collected from four native speakers producing five /ɹ/ types: three intervocalic retroflexes (an ambisyllabic retroflex preceded by a stressed lax vowel; a non-ambisyllabic retroflex preceded by a stressed tense vowel, hereafter non_A; and a non-ambisyllabic retroflex followed by a stressed vowel, hereafter non_B), as well as word-initial onset and word-final coda retroflexes. Tongue contours for each intervocalic retroflex were compared with those of onset and coda retroflexes using generalized additive mixed modeling (GAMM). Across speakers, intervocalic retroflexes followed a consistent trajectory, shifting from intermediate positions between onset and coda toward onset-like configurations. Crucially, this intermediate status was not unique to ambisyllabic retroflexes but was observed across all intervocalic contexts, suggesting that ambisyllabicity lacks a stable articulatory correlate and functions primarily as a theoretical construct. In addition, non_B retroflexes shifted toward onset-like tongue positions as early as the medial time point, whereas ambisyllabic and non_A retroflexes did so only at the final stage of articulation. This pattern indicates that intervocalic retroflexes preceded by a stressed vowel and followed by an unstressed vowel may be regarded as constituting an independent allophone, characterized by intermediate tongue contours that are distinct from onset and coda allophones.