Improving Speech Perception in Cochlear Implant Listeners through Enhanced Electrode-Neuron Interface
Cochlear implants (CIs) are the most successful neural prosthesis, and they help people
with severe to profound hearing loss access sounds by bypassing the damaged hair cells
in the inner ear and directly stimulating the auditory nerve fibers using an array
of electrodes. The electrical stimulation spreads from each electrode to the surrounding
spiral ganglion nerves (Sites A and B). The quality of these current spreads is impacted
by the quality of interface between CI electrodes and neurons. Limited spread (Site
A) allows for distinct sensations of frequency and speech information, while wider
spread increases the chance of channel interaction (Site B) and complicates differentiation
of sound frequencies allocated to these channels. We combine psychophysical, signal
processing, and neuroimaging methods as diagnostic precursors to assess the CI channel
functionality and develop efficient and selective stimulation strategies tailored
to individual CI listeners. The goal is to maximize the benefits of cochlear implants
and enhance the user's ability to hear and communicate.
Neurocognitive Mechanisms Linking Hearing Loss to Cognitive Decline and Dementia in Older Adults
This project examines how age-related hearing loss (ARHL) is associated with cognitive decline and dementia, and how psychosocial factors, neurocognitive mechanisms, and assistive devices (hearing aids and cochlear implants) may exacerbate or mitigate these effects. In collaboration with the USC Aging Brain Cohort (ABC) Study and the Aging Gracefully Lab, we employ a complementary set of behavioral and neuroimaging assessments—including MRI, DTI, and fNIRS—to test models in which ARHL contributes to structural and functional brain changes, social withdrawal, anxiety and depression, reduced cognitive engagement, and accelerated decline. We will test whether psychosocial resilience and hearing interventions reduce the adverse consequences of ARHL on cognitive decline. The knowledge gained will inform the development of interventions to preserve hearing, strengthen social engagement, and sustain cognitive health in older adults, ultimately improving quality of life and lowering dementia risk.
Language Development in Children with Cochlear Implants: The Role of Early Linguistic Environments
The role of properties of early language input on language outcomes of children with
CIs is not fully understood. We use the Language ENvironment Analysis (LENA) device,
a small, child-safe audio recorder that children wear for a day at a time, to record
and analyze adults’ language input and child vocalization. We use these recordings
to analyze acoustic-phonetic, lexical, morphosyntactic, and pragmatic information,
as well as the effects of caregivers’ speaking styles and the noise and reverberation
in the environment. Our goal is to provide new knowledge for evidence-based early
intervention strategies to clinicians and parents for maximizing the likelihood of
effective oral communication skills in children with CIs.
Consequences of Cochlear Implants for Voice and Speech Production
While the primary aim of cochlear implantation is to enhance the overall communication abilities of the recipients, the current evaluation of CI outcomes has predominantly concentrated on the auditory perceptual abilities. However, successful spoken communication necessitates not only efficient auditory perception but also precise speech production. The perception of talkers’ voice and vocal control in CI listeners remain poorly understood. We combine behavioral, electrophysiological (EEG), and functional neuroimaging (fNIRS) techniques for studying the ability of CI listeners in vocalization and perception of voice. The findings will provide important information on whether and to what extent CI impacts and restores the sensorimotor pathways in CI patients and how to improve diagnosis and targeted treatment for enhanced vocal control in CI patients.
Collaborations
Coordinator, Beth McCall, AuD, CCC-A
Department of Communication Sciences and Disorders
University of South Carolina
Director, Dr. Jean Neils-Strunjas
Department of Communication Sciences and Disorders
University of South Carolina
Director, Dr. Julius Fridriksson
Department of Communication Sciences and Disorders
University of South Carolina
Director, Dr. Rutvik Desai
Department of Psychology
University of South Carolina
Director, Dr. Julie Arenberg
Massachusetts Ear and Eye Infirmary
Department of Otolaryngology, Harvard Medical School
Director, Dr. Laura Dilley
Department of Communicative Sciences and Disorders
Michigan State University
Department of Speech, Language and Hearing Sciences
University of Connecticut