Research

Our faculty members work closely with undergraduate and graduate level students on a wide variety of research topics related to human communication and its disorders. Through a range of research experiences, our students have a unique opportunity to explore the boundaries of what is currently known on how we hear, perceive, produce and understand speech and language. Our students investigate innovative ways to assess and treat individuals with communication disorders in a dynamic and collaborative setting.

Below is a description of our labs, personnel, and some current or previous research activities.

The Aphasia Research Project is an active research environment devoted to the study of aphasia and related disorders.  After spending several years examining the nature of naming impairments in aphasia and Alzheimer’s disease, our current efforts are directed toward the development of effective treatment protocols for various aspects of aphasia, acquired alexia, and acquired agraphia.

My research projects are typically designed to address both clinical and theoretical issues in that a) treatments are theoretically motivated and b) patient responses to treatment often serve to clarify my theoretical perspective. Numerous single-subject research projects are underway and others are in the planning stages. Graduate students may become involved with our work in a variety of ways: clinical practicum in the Aphasia Clinic, independent study projects, thesis and dissertation research, or simply as participants in our weekly lab meetings. Our Aphasia Clinic includes an active Friday clinical schedule of aphasia groups devoted to maximizing communication effectiveness in individuals with a wide variety of aphasia types and levels of severity.

Work in the AHEAD lab is focused on the electrophysiology of infant speech perception. How do infants develop the capacity to hear and understand speech? What are infants’ speech feature detection and discrimination abilities? How can we assay those abilities using psychophysical (behavioral) and electrophysiologic methods?

To answers these questions, we undertake experiments that combine electrophysiologic and behavioral test paradigms. Because hearing sensitivity and (speech) signal audibility are crucial to speech perception, we are measuring thresholds for pure tones and speech using observer-based psychophysical procedures in infants 5-12 months of age. We also obtain recordings of brain wave activity from the auditory cortex (auditory evoked potentials) for the same stimuli. The auditory evoked potentials give us insight into the neural correlates of detection and discrimination for simple tones and more complex speech sounds. In another experiment, infants are taught to respond when they hear the difference between two similar speech sounds, such as “bah” and “dah.” Correct discrimination indicates the ability to hear the place-of-articulation speech feature. We also test for speech features of voice-onset-time (eg. “tah” vs. “dah”), manner (“bah” vs. sah”) and vowel height and place (/i/ vs. /u/ vs. /o/ vs. /a/). Complementary electrophysiolgic measures include the auditory steady state responses for multiple-mixed modulation stimuli and the cortical acoustic change complex. The ASSR test stimuli simulate the spectral and temporal characteristics of speech features and the ASSR response indicates how the brainstem auditory system processes each stimulus component. The cortical-evoked Acoustic Change Complex indicates the (cortical) neural capacity to detect the subtle acoustic differences that comprise discrimination ability.

Our efforts are focused on auditory development in early infancy because this is the period during which the early detection and intervention for hearing loss can have enormous benefit. It is important to study normal auditory system development so that we can translate our research findings into insights and methods that will allow us to successfully treat the infant with hearing loss.

The ACNE Lab addresses issues relating to the processing of complex acoustic signals such as speech, music, and other environmental sounds. Current projects include examining how people learn the sounds of a 2nd language and how one’s native language can interfere with this learning; investigating the ability of listeners to “tune” their perception to the particular characteristics of a speaker (e.g., understanding someone with a foreign accent or disordered speech); and studying how the design of cochlear implants and hearing aids can affect the ability of listeners to understand speech in complex listening environments. This multidisciplinary lab works closely with researchers in Psychology, Linguistics, Neurophysiology, and Electrical Engineering.

Research in this lab is concerned with auditory perception of complex sounds by human listeners. On the empirical side, we design and carry out behavioral (psychophysical) experiments to study listeners’ ability to extract useful information from various sounds, and how this ability is affected by hearing disorders. On the theoretical side, we construct computational models to characterize the listeners’ individual listening behavior, and to predict their performance in perceptual tasks. While the primary focus of our research is on the basic-science aspects of auditory perception, we also work on applied issues related to hearing, including the application of statistical and psychophysical principles and methods to the diagnoses of hearing disorders, and the signal processing for amplification.

Bilingual children acquire two languages in the same amount of time that monolingual children learn only one. How do they do that? The Bilingual Phonology Lab at the University of Arizona aims to find out. Little is known about typical phonological acquisition in bilingual children, and even less is known about bilingual children with phonological disorders. The long-term goals of the Bilingual Phonology Lab are to (1) determine the trajectory of typical acquisition in bilingual children, taking into consideration how the two languages of bilingual children interact; (2) determine how disorder presents itself in a child that maintains two speech sound systems, and (3) develop evidence-based assessment and intervention tools to help bilingual children with phonological disorders become effective communicators in both of their languages. Current studies in the Bilingual Phonology Lab examine bilingual phonological acquisition in the contexts of: (1) the Spanish stop-spirant alternation; (2) structural complexity related to consonant clusters; (3) cross-linguistic bootstrapping in bilingual preschoolers;(4) Voice Onset Time (VOT); (5) the morpho-phonemic interaction between English and Spanish, and (6) early, middle, and late-developing phonemes in English and Spanish.

Working memory and attention are strongly interdependent dimensions of language processing, yet the brain networks that underlie these cognitive functions are not well understood, especially in the auditory domain. The BLAMlab uses brain mapping methods like functional magnetic resonance imaging (fMRI), along with electrophysiological tools such as electroencephalography (EEG) and behavioral testing to study the neuroanatomical and functional organization of speech perception.

Currently funded projects involve the cognitive modulation of primary language processing by attention and memory networks, effects of attention type and cognitive load on language perception, and the roles of cortical-subcortical interactions in serving these cognitive processes. Current experiments are a prelude to studying clinical populations with brain disorders that may disrupt language, verbal memory, attention, or any combination of these skills.

My research efforts are concentrated on understanding receptive language, particularly as it relates to children with Specific Language Impairment (SLI). Currently, projects examining word learning with an emphasis on semantic features and phonology are underway. We are collecting data on children with SLI and typically developing children who are exposed to Spanish and English. Other projects are in the works. We’re building the stimuli for a treatment efficacy study that aims to improve syntax therapy for children with SLI. In collaboration with Dr. Cone-Wesson, we’re building an experiment to compare the speech perception of preschoolers with SLI to typically developing preschoolers. We often have opportunities for people to work either running subjects, analyzing or preparing data, or working in stimuli development.

Research in the Neurolinguistics Laboratory focuses on understanding the neural basis of language. We combine structural and functional neuroimaging techniques with linguistic analysis to study language processing, and how it breaks down in patients with different kinds of aphasia. We work with patients with aphasias of various etiologies, including stroke and neurodegenerative disease. Language domains of particular interest are syntactic processing and lexical access.

Current work in Dr. Plante’s lab focuses on learning and assessment. The lab is focused on discovering how both children and adults with developmental language disorders learn from a behavioral and neurobiological perspective. Behavioral studies are designed to determine what conditions facilitate rapid learning and whether those with language impairment benefit from the same factors that facilitate learning for non-impaired individuals. Functional magnetic resonance imaging studies are designed to examine whether the neural resources dedicated to learning are the same for imapaired and normal learners.

Assessment research is focused on the development and validation of language tests for use with children who have suspected language impairments.

Research in the Speech Acoustics Laboratory is focused on the use of computer models to aid in understanding how the physical shapes and sizes of both the voice source components and the vocal tract contribute to the sound of the human voice. Such a model is useful as a research tool for studying production and perception of normal and disordered speech. Projects are planned that continue development of a speech simulator based on data from the MRI studies capable of producing highly-intelligible, natural-sounding speech that can account for the multiple levels of information in the speech signal. Part of this work will involve use of x-ray microbeam data to investigate the temporal characteristics of speech production. The results of this research also have potential technological applications in such areas as speech synthesis, automated clinical speech analysis, speaker recognition for security purposes and forensic speech analysis. However, the goal is not to replace human vocal expression with simulated or synthesized voice, but rather to advance an understanding of how the many dimensions of the human voice function in order to transfer information and ideas to others.

Research in the SLAB lab focuses on speech and language processing across the lifespan in unimpaired individuals and in various populations with speech and/or language disorders, such as aphasia, apraxia of speech, and phonological disorders. An overarching question of interest is: What is the underlying nature of a given speech or language disorder? Two important features of most projects in the lab are (1) an emphasis on the time course of processing, that is, the unfolding over time of different processes involved in language comprehension or speech production, and (2) an emphasis on relating speech and language processing to other cognitive or perceptual skills, for example the relation between working memory and sentence comprehension, or the relation between motor control and language production.

The research in the SLAB lab combines a number of different methodological approaches and measures. Projects focusing on language comprehension use self-paced listening, self-paced reading, sentence-picture matching tasks, and (soon to come!) eye-tracking, and analysis of brain-behavior relations. Projects focusing on speech production use various priming tasks, acoustic analysis of speech, phonetic transcription, and analysis of brain-behavior relations. The research conducted in the SLAB lab is both theoretically motivated and clinically relevant.

There are various opportunities to become involved with the research in the SLAB lab, depending on your interests and time availability. To discuss these opportunities, or for more information about our research, please don’t hesitate to contact us.

Research projects in the speech research lab focus on normal and abnormal speech motor control. Many of the projects have been devoted to understanding the influence of development and aging on respiratory, laryngeal, and velopharyngeal function during speech production. Others have been designed to elucidate the impact of linguistic and biomechanic variables on speech physiology, vocal characteristics of skilled performers, and mechanisms underlying interactions between ventilatory drives and speech production requirements.

Research projects involving abnormal speech motor control have centered on a variety of neuromuscular disorders. For example, studies have been conducted to address questions regarding the speech of individuals with Parkinson disease, amyotrophic lateral sclerosis, cerebral palsy, spasmodic dysphonia, and spinal cord injury. A current emphasis relates to speaking-related dysprea (breathing discomfort associated with speech production) in health and disease. Another current emphasis is to elucidate the developmental time course for velopharyngeal closure for oral sound production in children. The overall goals of these research endeavors are to increase understanding of normal and abnormal speech production and to offer insights in potential clinical applications whenever possible.

At the Scottish Rite – U of A Child Language Center, our interests encompass clinical and educational services to preschool children with speech and language disorders, clinical training of undergraduate and graduate students, and research that will increase our understanding of children with impaired language skills. Programs involve our Wings on Words Preschool, Summer Day Camp, and Community Outreach Preschool Teacher Training Project. Independent study and volunteer opportunities are available in the Fall and Spring semesters as well as during Summer Session I. Training opportunities involve opportunities for students to facilitate the development of speech, language, and literacy of children with and without language impairment in the context of their daily preschool program. In this setting, students are involved in planning and implementing individual, small-group, and classroom activities with all children in the school. Throughout these experiences, students have the opportunity to observe speech-language therapy sessions and help extend therapy gains into the classroom. Wings on Words is also a clinical practicum site for graduate students pursuing their masters in speech-language pathology and audiology.