My research revolves around speech production, and in particular around the processes involved in planning the sounds and movements of speech. Most of us have no difficulty with speech production, and we rarely think about the complexities involved in making fast, precise, and coordinated movements to create an acoustic signal that a listener can understand. However, for some people, speaking is difficult and may lead to misunderstanding. For example, children learning to speak often make speech errors; some children have a speech disorder for no obvious reason; and some adults have a speech disorder after a neurological injury (e.g., a stroke).
In my lab, we study speech production in children and adults with and without speech disorders. The long-term goals are (1) to deepen our understanding of this complex behavior in typical and atypical speakers, and (2) to improve diagnosis and treatment of speech disorders. We use a range of experimental tasks and measures to understand speech planning and production, including picture naming tasks in which we look at reaction times (to capture speech planning demands in real time), acoustic measures (to examine the details speech motor control), and perceptual judgments of speech accuracy (to examine the effects on communication).
Research Project 1: Speech Planning and Production in Children with and without Speech Disorders (funded by NIH, K01 DC010216)
Children with speech disorders constitute up to 50% of the caseload of speech-language pathologists in schools, yet our ability to identify and characterize underlying problems is limited. Further, these processes remain poorly understood even in typical children. In four experiments, we compare how children with and without speech disorders plan speech, with an emphasis on the units and time course of speech planning. Analyses to date reveal interesting differences in how adults and typically-developing children plan and produce speech; children appear to plan their speech using larger “building blocks” of sound than adults. Compared to typically developing peers, children with motor-based speech disorders appear similar with respect to the size of building blocks of sound, but differ in coordination of speech movements.
Research Project 2: Speech Planning and Production in Apraxia of Speech and Aphasia (funded by the American Speech-Language-Hearing Foundation)
In this project, we study speech planning in adults with a speech disorder called apraxia of speech (AOS) or a language disorder called aphasia. AOS is the primary disorder in ~4% of neurogenic communication disorders, and ~1 million people in the US have aphasia, with 80,000 new patients every year. Accurate characterization of impairments and differential diagnosis remain challenging. Our findings to date show that speakers with AOS (but not speakers with aphasia) have impaired speech motor plans, and also have difficulty accessing these plans.
Research Project 3: Improving Treatment for Childhood Apraxia of Speech (funded by Childhood Apraxia of Speech Association of North America)
In this project, we compared the effects of different treatment conditions on speech accuracy in children with childhood apraxia of speech. Using single-case experimental treatment designs, we demonstrated clear treatment effects, and found that practicing targets in blocked order was more beneficial than practicing targets in random order, and that providing verbal feedback after every attempt was not as effective as providing feedback only half the time.