Phonological implications of covert articulatory variation

The most obvious difference between spoken languages is that they sound different from one another. The sounds of language interact with each other according to patterns that can be attributed to the human vocal tract, auditory system, and memory, but these patterns vary arbitrarily from language to language and dialect to dialect. Understanding how each language and dialect came to be the way it is requires understanding how languages change. A lingering mystery is why language change occurs abruptly in certain times and places but not in others, when the phonetic motivations for language change are ever-present. Unlocking this and other puzzles about variation and change in linguistic sound systems provides a window into cognition, physiology, social interaction, and how these interact with each other.

This project is a laboratory study of language variation and change, informed by a database of phonological patterns in several hundred languages and a database of hundreds of hours of spontaneous speech from one English-speaking community. The project tests the hypothesis that the start of language change is favored by covert differences in articulation, i.e., cases where speakers of the same language produce speech sounds using their vocal tracts in different ways, even though the sounds they make are indistinguishable to listeners under most conditions. Different speakers producing the same speech in different ways is hypothesized to be an important source of variation that drives language change. The random alignment of covert articulatory differences with social structure is hypothesized to account for the abruptness and infrequency of sound change. The research team examines three known cases of covert articulatory variation in English and assesses their impact on a range of sound patterns active in Raleigh, NC. The project augments an existing collection of 200+ sociolinguistic interviews with ultrasound video of the tongue, airflow measurement from the nose and mouth, and perception data. The research team will develop tools for rapid and flexible analysis of large quantities of articulatory data. These tools will be shared publicly, with the potential to benefit other linguists, speech pathologists, and engineers. The project expands and upgrades a public database of sound patterns in several hundred languages. The speech sounds focused on by the project include ones that are challenging to English-learning children and adults. Detailed phonetic information will be shared with the speech pathology and language teaching communities. Graduate and undergraduate students working on this project will learn innovative laboratory methods and quantitative skills.