Psychophysical based channel selection
Research type
Research Study
Full title
Psychophysics for Optimising Cochlear Implant Channel Selection
IRAS ID
224548
Contact name
Patrick Boyle
Contact email
Sponsor organisation
University of Cambridge
Duration of Study in the UK
0 years, 5 months, 28 days
Research summary
Cochlear implants (CIs) are devices that provide some hearing to people who have profound or total hearing loss via electrical stimulation of the auditory nerve. CIs work by filtering the sound picked up by a microphone into several frequency bands or “channels”. The pattern of amplitude modulation in each channel is extracted and used to stimulate a single electrode within the cochlea.
The benefit obtained from a CI varies widely across users. Poor performance may occur when one or more electrodes stimulates a place in the cochlea where there are few or no surviving neural processes. The channels driving those electrodes are referred to as “bad” channels. A CI user may perform better if the bad channels are deactivated. The experiment proposed here will evaluate a method for identifying bad channels.
The “target signal” will be amplitude modulation applied to a sinusoidal carrier frequency that falls at the centre frequency of the “target channel”. The task will be discriminate a change in the pattern of amplitude modulation in the target signal. Interfering sounds will also be amplitude modulated sounds, but the carrier frequencies of these sounds will be chosen so that they stimulate channels adjacent to the target channel. We will measure the ability to detect changes in the target amplitude modulation as a function of the depth of amplitude modulation on the adjacent interfering channels channels. This process will be repeated using each channel in turn as the target channel. Bad channels will be identified as those that are strongly affected by the amplitude modulation in the interfering channels.
Having identified any bad channels for a specific CI user, we will assess whether deactivating the bad channels improves the ability to understand speech using the CI.
REC name
East Midlands - Nottingham 1 Research Ethics Committee
REC reference
17/EM/0222
Date of REC Opinion
28 Jun 2017
REC opinion
Further Information Favourable Opinion