The seeds and spread of sound change: Individual differences in coarticulatory patterns

University Of California-Davis, Davis CA

Investigators

Abstract

This project investigates contextual variation in the pronunciation of consonants and vowels when they occur next to other sounds. This is known as 'coarticulation'. An example is that when pronouncing the word 'bone', speakers begin the movement needed to produce the nasal 'n' sound early, during the pronunciation of the preceding 'o' vowel. What aspects of this articulatory overlap are universal across speakers and what aspects can vary across speakers? This project addresses that question by examining how speakers of American English vary in their coarticulation patterns producing the same set of words. Since coarticulation provides advance information about upcoming sounds in the word, it can be used predictively by listeners to comprehend speech more efficiently. How do listeners adapt to cross-speaker variation when using coarticulation to comprehend speech? This question is addressed by investigating how listeners track and use cross-talker coarticulatory variation during word comprehension. Finally, coarticulation has played a prominent role in explaining common historical sound changes, and this project addresses the role of coarticulatory variation in leading to historical variation across languages. This research will contribute to our basic understanding of speech and can facilitate better treatment of speech and language disorders. It will also contribute to the training and mentoring of a future generation of scientists (including undergraduates, graduate students, and a postdoctoral researcher). The project's first objective is to characterize individual differences in coarticulation using acoustic and perceptual assessments. Experiment 1 identifies talker-specific relationships between prosodic organization, nasal-coarticulatory, oral articulations, and voice quality in order to typologize the coarticulation production grammars of 100 speakers of American English. Experiment 2 perceptually defines individual variation in the grammatical specification of coarticulatory vowel nasalization produced by these speakers. The goal is to typologize cross-speaker variation using the same conventions used to define cross-linguistic coarticulatory variation, relating synchronic coarticulatory variation across individuals to cross-linguistically phonologized phonetic patterns. The prediction is that the types of variation in produced coarticulatory patterns that are seen across languages also exist systematically across individual speakers. Objective 2 is to investigate the influence of perceptual learning of talker-specific coarticulatory patterns on listener-based sound change mechanisms. Experiments 3 and 4 investigate perceptual adaptation to talker-specific patterns of coarticulation, exploring how listener adaptation to talker-specific coarticulation patterns is an integral mechanism of phonologization. The prediction is that perceptual learning of coarticulation is helpful because it allows listeners to both be flexible and predict how a given talker is going to produce a word. This mechanism can also be integrated into listener-oriented mechanisms of sound change to explain how different coarticulation patterns phonologize. The project tests novel extensions of listener-based sound change accounts that integrates perceptual adaptation to talker-specific coarticulatory patterns in order to account for how novel coarticulatory patterns phonologize. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.