Improved stereo separation for bilateral bone-anchored hearing aids.

Bone-anchored hearing aids (BAHAs) restore hearing to patients with hearing losses located in the middle or outer ear. They vibrate the patient’s skull, and sound is transmitted directly to the inner ear through the bone. There is a growing market; once made exclusively by our collaborators, Cochlear Bone-Anchored Solutions, bone-conduction hearing aids are now also made by Oticon, Sophono and MedEl.
Patients are usually fitted with a single BAHA, because each device stimulates both inner ears; this "cross-talk" limits stereo separation. Stereo hearing is important for telling what direction sounds come from ("sound localisation") and also for understanding speech in background noise.

The project, sponsored by Action on Hearing Loss, will develop a way to fit bilateral BAHAs which deliver better stereo separation using a method called “cross-talk cancellation”. Better stereo separation should improve the patient’s sound localisation and understanding of speech in noise.

To cancel cross-talk, one needs to have precise measurements of the differences between the waveforms received by each inner ear when each BAHA is activated. We have developed and tested methods for doing this in normally hearing listeners using a bone vibration device. We have also used the data to cancel, at one ear, the noise produced by one bone vibrator, by adding a cancellation signal using a second bone vibrator. The cancellation signal improved the intelligibility of speech presented by the 2nd bone vibrator, because the noise had been suppressed at one ear. The next stages are to 1) get the method working in both ears simultaneously using cross-talk cancellation signals for both sides 2) measure the resulting benefit to speech understanding 3) measure the benefits to sound localisation and 4) apply the technique to patients with bilateral BAHAs.

The project has its technical aspects, but is more concerned with psychophysical measurement and software development than engineering.

Applicants should apply to the Doctor of Philosophy in Psychology with a start date of October 2020.

In the research proposal section of your application, please specify the project title and supervisors of this project and copy the project description in the text box provided. In the funding section, please select ’I will be applying for a scholarship/grant’ and specify that you are applying for advertised funding from Improved stereo separation for bilateral bone-anchored hearing aids.