Doctoral Dissertation Research: Learning of Novel Phonetic Categories After Training in Perception and Production

Northwestern University, Evanston IL

Investigators

Abstract

Humans possess a remarkable ability to produce and understand speech. In order to successfully learn a language, an individual must learn what the sound categories in a particular language are and what makes various sounds different from one another. For instance, "r" and "l" belong to different sound categories in English, but not in some other languages. Learning how to differentiate between these sounds and produce them is an important part of learning a language. Currently much is known about how listeners learn to perceive the speech sound categories; however, significantly less is known about how speakers learn about speech categories in production and how learning in one modality (i.e., perception or production) is related to learning in the other modality. The relationship between perception and production could take many forms. Learning in one modality could always lead learning in the other (i.e., an individual would have to be able to perceive a distinction before they could produce it). Category formation could occur in parallel for both modalities (i.e., both perception and production could learn about new sounds simultaneously). Alternately, learning in one modality could actually hinder learning in another modality (e.g., learning in speech production could disrupt learning in speech perception). This study aims to differentiate among these hypotheses. The experiments in this study are designed to train participants on novel sound categories with the training focusing on either perception or production. Then participants are tested in both perception and production. Untangling how new sound categories are formed and accessed in the two modalities will give insight not only into the learning process of new sound categories but also into how the two modalities are related. The findings of this study will be significant in both theoretical and applied domains. Having a better understanding of how categories are formed will help inform theories of learning for both first- and second-language learners. Understanding how speech perception and production are related will be informative in the development of models of speech processing in both perception and production. In the applied domain, understanding how perception and production interface, particularly at the level of sound categories, will be beneficial for second-language teachers. Furthermore, clinicians, such as speech-language pathologists, will benefit from a better understanding of how the two modalities interact when learning (or re-learning) novel sound categories. For instance, if patients have an impairment in speech production, they may be able to use their intact perceptual abilities to re-train the impaired modality.