Uniformity in phonetic realization: Evidence from sibilant place of articulation in American English

Phonetic realization is highly variable and highly structured within and across talkers. We examine three constraints that could structure the phonetic space of related speech sounds: target, contrast, and pattern uniformity. Target uniformity requires a uniform mapping from distinctive features to their corresponding phonetic targets within a talker, contrast uniformity requires a consistent difference in the phonetic targets that realize featural contrasts across talkers, and pattern uniformity requires a uniform template of phonetic targets across talkers. Focusing on American English sibilant fricatives, we measure and compare each constraint's influence on the phonetic targets corresponding to place of articulation. We find that target uniformity is the strongest constraint: each talker realizes a given distinctive feature value in highly similar ways across related sounds. Together with similar findings for other sound classes, this result reveals fine-grained systematicity in the mapping from phonology to phonetics and has implications for theories of speech production and speech perception.