Acoustically-Evoked Electrical Cochlear Response Amplitude-Growth Function as Objective Method to Program a Cochlear Implant: Preliminary Results

Background: Amplitude-growth function has been used to find the electrically evoked Compound Action Potential threshold which can be used to programming a cochlear implant sound processor.

Objective: The aim of this research was to elicit an Electrical Cochlear Response (ECR) using an acoustic stimulation and to derive an alternative amplitude-growth function in multichannel cochlear implant users.

Methods: ECRs have been recorded from 8 unilateral cochlear implant adult users in response to pip stimuli, varying their frequency according to the frequency-to-electrode mapping. Multivariate empirical mode decomposition was used to remove cochlear implant artefact from recordings. ECR amplitude-growth functions were calculated using at least 4 intensities from 10 to 50 dBHL, depending on detecting ECR threshold. Slope of amplitude-growth function was calculated electrode by electrode; between four and seven for each subject.

Results: In general, it is possible to observe different amplitude-growth function slopes from basal to apical electrodes. Additionally, significant correlations between ECRs and audiometric thresholds were found.

Conclusions: Although it is necessary to increase the number of studies, our results could be useful to derive electrode stimuli current levels to fit the dynamic range of cochlear implants, using acoustical instead of electrical stimuli.

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