Researchers have succeeded for the first time in measuring brainwaves directly via a cochlear implant, which indicate in an objective way how good or bad a person's hearing is.

A cochlear implant enables people with severe hearing loss to hear again. An audiologist adjusts the device based on the user's input, but this is not always easy, according to researchers, including Ben Somers from Katholieke Universiteit (KU) Leuven in Belgium. "We used an experimental implant that works exactly the same way as a normal implant, but with easier access to the electronics", said Somers. "A cochlear implant contains electrodes that stimulate the auditory nerve. This is how sound signals are transmitted to the brain. In our research, we have succeeded in using these implanted electrodes to record the brainwaves that arise in response to sound", Somers added.

The study, published in the journal Scientific Reports, indicates that the findings are important for the further development of smart hearing aids. According to the researchers, children who are born deaf or elderly people with dementia have more difficulty in assessing and communicating how well they hear the sounds, which may result in an implant that is not optimally tuned to their situation.

A possible solution is to adjust the implant based on brain waves, which contain information about how the person processes the sounds that they hear, the researchers said. This kind of objective measurement can be made with an electroencephalogram (EEG), whereby electrodes are placed on the head. However, it would be more efficient if the implant itself could record the brainwaves to measure hearing quality, they added.