Combination treatments in hearing loss to improve speech understanding
Why do combination treatments for hearing loss need investigation?
Initially, cochlear implants were provided only to people who were profoundly deaf, but it is now routine in people with partial hearing loss.
A combination of stimulation via a cochlear implant and a hearing aid in the same ear has been shown to improve speech understanding, particularly in noisy environments, and to increase the aesthetic quality of sound.
However, nothing is known about the physiological mechanisms underlying these benefits.
The aim of our research is to address this knowledge gap by measuring the patterns of neural activity in the auditory centre of the brain evoked by speech sounds.
We will then assess how the pattern of neural activity relates to discrimination between the different speech sounds, which is a vital aspect of hearing.
Next steps for Bionics Institute researchers
Our goal is to understand how the electrical stimulation from the cochlear implant and the acoustic information amplified by a hearing aid is combined in the brain to produce a unified perception of sound.
This will inform clinical decisions on providing this combination to patients to treat hearing loss.
The research team
Bionics Institute researchers:
Professor James Fallon, Professor Dexter Irvine, A/Prof Andrew Wise and Dr Alex Thompson.
Melbourne University researcher:
Professor David Grayden.
More information for researchers
This project aims to establish how combined acoustic and electrical stimulation is processed and integrated in the auditory brain.
The expansion of criteria for cochlear implantation to include subjects with substantial residual hearing and the development of minimally traumatic implantation procedures to preserve residual hearing has focused interest on the benefits of combined electro-acoustic stimulation.
In electro-acoustic stimulation, electrical stimulation is delivered to the basal, high-frequency end of the cochlea while acoustic stimulation is delivered to the apical, low-frequency end (typically with acoustic amplification over the range of residual hearing).
Although a variety of fitting procedures have been employed for both electrical and acoustic stimulation, the general finding is that electro-acoustic stimulation provides better speech perception, particularly of speech in noise, than electrical stimulation alone.
However, the physiological basis for the benefits provided by electro-acoustic stimulation, and the interactions between the neural activity evoked by acoustic and electrical stimulation, are not well understood.
The aim of this project is to provide the first detailed information on the way in which electro-acoustic stimulation is processed in the central auditory system.
Publications
Fallon, J.B., Dueck, W., Trang, E.P., Smyth, D., Wise, A.K., 2022. Effects of chronic implantation and long-term stimulation of a cochlear implant in the partial hearing cat model. Hearing Research, Accepted.
