Channel Interaction in Cochlear Implant and Speech Understanding in Noise

Study Overview
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Brief Summary
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The goal of this study is to take into account channel interaction in the cochlear implant (CI) fitting process. Designing a fast and accurate method of measurement would help to customize the fitting procedures to patients' specificities in order to maximize speech understanding in every day conditions especially in noise.

Official Title
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Impact of Channel Interaction on Cochlear Implant Performances in Noise : Influence of the Number of Maxima.

Conditions
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Cochlear Implants

Intervention / Treatment
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* Other: speech audiometry in noise
* Other: Psychophysical tuning curves in forward masking
* Other: Electrically-evoked Auditory Brainstem Response (EABR)
* Other: Tonal audiometry
* Other: Auditory canal examination


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Fluent in French Able to understand written instructions Under French public medical insurance Normal-hearing subjects only: Adult between 18 and 50 years old Without a remarkable otological medical history, for example: chronic otitis, trans-tympanic tubes and / or all ear surgeries; Clear auditory canal and normal eardrum; Average audiometric loss under 20 decibels Hearing Level (dB HL) Cochlear implant users only: Adult between 18 and 60 yo Normal middle ear Used the cochlear implant for more than a year Wearing a device from the company Neurelec/Oticon Medical Exclusion Criteria: Behavioral and/or neurological disorders Proven psychological disorder Use of psychotropic medication People who experience migraine attacks on a regular basis Use of ototoxic medication Exposed to loud noises within the last 72 hours Included in another clinical trial that uses medication

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Cochlear implant users<br>Adult cochlear implanted patients wearing an Oticon Medical/Neurelec device will have speech audiometry test in noise, psychophysical tuning curves in forward masking and Electrically-evoked Auditory Brainstem Response (EABR) measurement | Other: speech audiometry in noise<br>* Subjects will be asked to repeat lists of words played by speakers in a noisy environment generated by the same speakers. A percentage of correct recognition is calculated for each list.<br>Other: Psychophysical tuning curves in forward masking<br>* Sounds of variable center frequency are used as maskers, and a tone with a fixed frequency at a fixed level is the target. What is tested here is the level of masker that just masks the target.<br>Other: Electrically-evoked Auditory Brainstem Response (EABR)<br>* Channel interaction assessment using eABRs (auditory nerve responses). The method consists of two measurements: 1) eABR measurements with stimulation by a single electrode of the cochlear implant at 70% of the dynamic range (four different electrodes are tested); 2) Measurement of a single eABR with stimulation from all four electrodes at 70% of the dynamic range. A comparison of the eABRs obtained by these two measurements, indicates the electrical and neural interactions between the electrodes.<br>|
| Active Comparator: Normal-hearing subjects<br>Normal-hearing subjects will have speech audiometry test in noise, psychophysical tuning curves in forward masking, auditory canal examination and tonal audiometry | Other: speech audiometry in noise<br>* Subjects will be asked to repeat lists of words played by speakers in a noisy environment generated by the same speakers. A percentage of correct recognition is calculated for each list.<br>Other: Psychophysical tuning curves in forward masking<br>* Sounds of variable center frequency are used as maskers, and a tone with a fixed frequency at a fixed level is the target. What is tested here is the level of masker that just masks the target.<br>Other: Tonal audiometry<br>* Tonal audiometry will be performed with headphones<br>Other: Auditory canal examination<br>* Otoscopic examination of external auditory canal and eardrum<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of syllable correctly recognized during speech audiometry test | Subjects will be asked to repeat lists of words played by speakers in a noisy environment generated by the same speakers. A percentage of correct recognition is calculated for each list. | At inclusion | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Sound masking threshold | Measurement of channel interaction by establishing psychophysical tuning curves in forward masking. Sounds of variable center frequency are used as a masker, and a tone with a fixed frequency at a fixed level is the target. What is tested here is the level of masker that just masks the target. | At inclusion | 
| Electrically-evoked Auditory Brainstem Response (eABR) | Channel interaction assessment using eABRs (auditory nerve responses). The method consists of two measurements: 1) eABR measurements with stimulation by a single electrode of the cochlear implant at 70% of the dynamic range (four different electrodes are tested); 2) Measurement of a single eABR with stimulation from all four electrodes at 70% of the dynamic range. A comparison of the eABRs obtained by these two measurements, indicates the electrical and neural interactions between the electrodes. | Up to 12 months after inclusion | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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speech audiometry, psychophysical tuning curve, electrophysiology, auditory brainstem response