Impact of ASL Exposure on Spoken Phonemic Discrimination in Adult CI Users: A Functional Near-Infrared Spectroscopy...

Area of Science:

• Neuroscience
• Linguistics
• Audiology

Background:

• Deaf individuals with cochlear implants (CIs) face challenges in spoken language phonemic discrimination.
• The impact of early signed language exposure on neural processing of spoken language in deaf CI users is not fully understood.

Purpose of the Study:

• To investigate how the age of American Sign Language (ASL) exposure affects spoken language phonemic discrimination in deaf individuals with CIs.
• To examine the neural correlates of phonemic discrimination in deaf CI users with varying ASL exposure histories.

Main Methods:

• Functional near-infrared spectroscopy (fNIRS) neuroimaging was used to monitor brain activity.
• Deaf CI users and hearing individuals completed phonemic discrimination tasks in English and Hindi.
• Participants' age at cochlear implantation and age of ASL exposure were recorded.

Main Results:

• Deaf CI users with early cochlear implantation showed better English phonemic discrimination than those with later implantation.
• Early-life language exposure, regardless of modality (signed or spoken), was linked to increased left-hemisphere language area activation.
• Early ASL exposure correlated with enhanced neural activation for native vs. non-native phonemic contrasts in deaf CI users with later implantation.

Conclusions:

• Early signed language exposure does not hinder spoken language processing in deaf CI users.
• Early ASL exposure may mitigate the adverse effects of pre-implantation language deprivation.
• Findings support the integration of signed language in the auditory rehabilitation of deaf children with CIs.