Ryan Barnsley is a PhD student in Professor John Culling’s lab at Cardiff University. His studentship began in 2020.
Bone-anchored hearing aids (BAHAs) restore hearing to people with hearing loss caused by problems in the middle or outer ear. BAHAs vibrate the person’s skull, and sound is transmitted directly to the inner ear through the bone.
Stereo (binaural, or ‘2-eared’) hearing is important for telling what direction sounds come from and for understanding speech in noisy environments. A person is usually fitted with a single BAHA on 1 side of the head because each device stimulates both the left and right inner ears. This means that the sound signals transmitted from the BAHA are mixed between both ears. This mixing of sounds, or ‘cross-talk’, between the ears limits a person’s stereo hearing. This means that it’s very difficult for them to tell where sounds are coming from and to understand speech in noisy environments.
The researchers have developed a way to cancel cross-talk between the ears when a bone vibration device is used by people with normal hearing. They’ve done this by adding a cancellation signal using a second bone vibrator. The cancellation signal suppressed the noise at 1 ear, and this meant that speech presented by the second bone vibrator was clearer and more understandable.
The overall aim of the project is to develop a way to fit bilateral BAHAs (a BAHA for each ear) that deliver better stereo hearing by using ‘cross-talk cancellation’.
The project involves 4 stages:
- getting the cross-talk cancellation to work in both ears at the same time
- measuring how much this improves a person’s ability to understand speech
- measuring how much this improves a person’s ability to locate where sounds are coming from
- applying the technique to patients with bilateral BAHAs to understand if this can be practically implemented.
This project will benefit people who have hearing loss due to bilateral congenital deformations of the middle ear, and cholesteatoma (abnormal, non-cancerous skin growth in the middle ear). These conditions often affect both ears and cannot be repaired with middle ear surgery, so BAHAs are the only treatment option.
Cross-talk is a major limiting factor in the quality of hearing that can be provided by two BAHAs. By reducing cross-talk, this project will enable people with hearing loss to benefit more from the fitting of two BAHAs.
The project is expected to improve stereo hearing, which will give BAHA users an improved ability to identify where sounds are coming from and to understand speech in noisy environment.