Assessment of the feasibility of optimising hearing aid fitting in adult unilateral cochlear implant users who have residual hearing in their non-implanted ear

Chief investigator

Dr Pádraig Kitterick

Study team

Dr Claire Fielden


NIHR Nottingham Hearing Biomedical Research Unit

Study period


Bimodal listening is when acoustic information from a hearing aid in one ear is combined with electric information from a cochlear implant in the other ear. There is now a large body of evidence that suggests that bimodal fitting may be more beneficial than use of either device alone. Wearing a hearing aid with a cochlear implant can provide advantages such as improved speech understanding in noise, melody recognition, speech quality perception and sound localisation.

However, many studies reporting these ‘bimodal benefits’ are conducted outside the UK in countries with different eligibility criteria for implantation. Bimodal listeners, therefore, tend to have a greater degree of hearing in their non-implanted ear than is typically seen in the UK. Unsurprisingly, some studies with UK bimodal users have not shown as clear a bimodal advantage as other non-UK studies. However, in spite of the poorer hearing thresholds in the contralateral aided ear, some UK patients do report benefits from wearing a hearing aid in addition to using an implant. Other users, however, report little advantage to wearing the two devices, preferring to listen through their implant alone.

As adult patients in the UK receive a cochlear implant in one ear only, there is a need to evaluate treatments which may provide them with the opportunity to listen with two ears. Hearing aid fitting in their non-implanted ear is a relatively low-cost intervention that has the potential to improve listening outcomes in unilateral cochlear implant recipients. However, guidelines for providing hearing aids in implant users and for optimising bimodal listening are currently not available to clinicians in the UK. This study will examine why some implant users in the UK choose to continue to use a hearing aid with their implant, despite their limited hearing, and what benefits they get from using their hearing aid. It will also assess the feasibility of conducting future studies to evaluate different methods of fitting hearing aids in UK cochlear implant users to improve their bimodal listening skills.