An EEG measure of sound localisation with bilateral cochlear implants
Research type
Research Study
Full title
An EEG measure of sounds localisation when listening with bilateral cochlear implants
IRAS ID
166420
Contact name
NIcholas Haywood
Contact email
Clinicaltrials.gov Identifier
R&D reference number, 14/0809; Data Protection Registration number, Z6364106/2014/10/82
Duration of Study in the UK
0 years, 9 months, 1 days
Research summary
Cochlear implants can provide hearing for the severely deaf, and some people have cochlear implants in both ears (bilateral implants). However, bilateral users do not typically receive the full benefit of hearing with two ears (binaural hearing). Normal hearing listeners are able to use small timing differences in the arrival of a sound to both ears to estimate the location of a sound in space (interaural timing differences, ITDs), but bilateral implant users are typically much less sensitive to use this cue.
We will test an electroencephalographic (EEG) measure of binaural hearing with bilateral cochlear implant listeners - we aim to measure of sensitivity to ITD. Using EEG, we will measure the brain’s response (evoked auditory responses). We will present a sound stimulus that contains a series of abrupt changes in ITD. Here, a listener who is sensitive to ITDs would perceive an on-going sound that jumps between the left and right side of space. If the listener is sensitive to ITDs, we would expect to observe an evoked response to each change in interaural timing difference. Pilot studies have observed such responses in normal hearing volunteers.
Cochlear implants contain several electrodes, each capable of delivering stimulation. For a bilateral implant user, it is important that the electrodes in each ear are matched, so that a sound of a given frequency stimulates two electrodes with similar positions in both ears (this matching can be controlled with the implant’s software). After presenting stimuli to a variety of different bilateral electrode pairs, the electrode pairing that elicits the largest evoked response to interaural timing difference changes may be the best matched pair. As such, the measure may prove a clinically viable tool for electrode matching. This is an explorative study, and the clinical settings of volunteer’s cochlear implants will not be modified.
REC name
London - Camberwell St Giles Research Ethics Committee
REC reference
15/LO/0606
Date of REC Opinion
30 Mar 2015
REC opinion
Favourable Opinion