Degenerative Consequences of Congenital Deafness

Study Overview
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Brief Summary
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In this study, the investigators will study one of the basic biophysical properties of the auditory nerve, charge integration, behaviorally (detection threshold versus phase duration functions). The investigators will compare charge integration in two subject groups: congenitally deafened and deafened at a later age in life. The investigators will then examine if behaviorally estimated neural excitation patterns differ between short phase duration and long phase duration stimulation. Lastly, The investigators will measure if speech recognition improves with using long phase duration stimulation, relative to using the standard default short phase duration stimulation. The primary endpoint of the study is speech recognition, and the secondary endpoints are the steepness of the detection threshold versus phase duration functions, and the width of psychophysically estimated neural excitation.

Official Title
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Degenerative Consequences of Congenital Deafness

Conditions
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Congenital Deafness

Intervention / Treatment
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* Behavioral: Phase duration


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Cochlear Nucleus cochlear implant users or Advanced Bionics cochlear implant users Native speakers of English Early onset of deafness (< 3 years of age); no requirement for age at implantation Late onset of deafness (> 3 years of age); matched in duration of deafness to the early onset group Has had device experience for at least one year Can be child or adult at the time of enrollment Exclusion Criteria: None

Ages Eligible for Study
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Minimum Age: 15 Years

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Cochlear implant users with late-onset deafness<br>Examine charge integration (Detection threshold as a function of phase duration). Examine neural spatial excitation patterns with long and short phase duration. Measure speech recognition using long and short phase duration stimulation patterns. | Behavioral: Phase duration<br>* We will vary the phase duration in the stimulation, and examine detection threshold, spatial spread of neural excitation, and speech recognition as the outcomes.<br>|
| Cochlear implant users with early-onset deafness<br>Examine charge integration (Detection threshold as a function of phase duration) and compare that with the late-onset group. Examine neural spatial excitation patterns with long and short phase duration within the non-leaky phase duration range. Measure speech recognition using long and short phase duration stimulation patterns. | Behavioral: Phase duration<br>* We will vary the phase duration in the stimulation, and examine detection threshold, spatial spread of neural excitation, and speech recognition as the outcomes.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Slope of the strength duration function | Subjects will be measured for detection thresholds as a function of phase duration of the pulse train and the slope of the function will be derived. | starting 6 months post award notice and will take up to 4 years to complete | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Psychophysically estimated neural excitation width | Subjects will be measured for psychophysical forward-masked spatial tuning curves using stimuli with long and short phase duration. | starting 6 months post award notice and will take up to 4 years to complete | 
| Speech recognition using long phase duration | Subjects' speech recognition performance will be evaluated using CUNY and TIMIT sentences with long and short phase duration stimulation. | starting 6 months post award notice and will take up to 4 years to complete |