Optimizing Bilateral and Single-sided-deafness Cochlear Implants for Functioning in Complex Auditory Environments

Cochlear implants (CIs) are devices that partially restore hearing for people with severe to profound hearing loss. This research focuses on CI users who use bilaterally implanted devices (two CIs, one on each side) and also "single-sided deafness" (SSD) CI users who use one CI together with good acoustic hearing in their opposite ear. The goal is to measure and understand the impact of large input asymmetries across the two ears. These asymmetries are common in BI-CI listeners and always present in SSD-CI users. Although most CI listeners benefit from a second source of auditory input, this project measures how these asymmetries limit speech understanding and spatial hearing. The long-term goal is countering or compensating for input asymmetries. Electrophysiological measures are used to describe the health of the auditory system. Behavioral measures are used to assess if training improves performance. CT imaging is utilized to describe the placement of the CIs.


Eligibility Criteria:
For Bilateral Cochlear Implant Users Arm:

Inclusion Criteria:

* two cochlear implants
* acquired their hearing loss during adulthood or late childhood (post-lingual onset)
* native English speaker
* primarily use oral language
* at least six months of cochlear implant use
* Sufficient corrected or uncorrected visual acuity (20/50 or better) to read large-font text

Exclusion Criteria:

* people who do not use oral language will be excluded.
* people with less than six months of device use will be excluded
* other known disability or neurological disorder
* women who are pregnant will be excluded from the CT portion of the study
* people with any unaided audiometric tone-detection threshold better than 60 dB HL at standard audiometric frequencies (250-8000 Hz) in either ear will be excluded

For Unilateral Cochlear Implant User with Single-Sided Deafness Arm:

Inclusion Criteria:

* one cochlear implant in one ear and a second ear with some acoustic hearing
* acquired their hearing loss during adulthood or late childhood (post-lingual onset)
* native English speaker
* primarily use oral language
* at least six months of cochlear implant use
* Sufficient corrected or uncorrected visual acuity (20/50 or better) to read large-font text

Exclusion Criteria:

* people who do not use oral language will be excluded.
* people with less than six months of device use will be excluded
* other known disability or neurological disorder
* women who are pregnant will be excluded from the CT portion of the study
* people with any unaided audiometric tone-detection threshold better than 60 dB HL at standard audiometric frequencies (250-8000 Hz) in the implanted ear will be excluded
* people with an acoustic pure-tone average threshold (octave frequencies 250-4000 Hz) \> 30 dB HL in the non-implanted ear

For Non-Implanted Listeners with Acoustic Hearing Arm:

Inclusion Criteria:

* audiometrically normal hearing or near-normal hearing, or mild/moderate hearing loss
* Sufficient corrected or uncorrected visual acuity (20/50 or better) to read large-font text

Exclusion Criteria:

* severe hearing loss
* other known disability or neurological disorder