Although cochlear implants do allow some deaf people to hear again, adjusting the devices to individual users can be challenging. An experimental new implant is designed to help in that regard, by reading the user's brain waves.
Putting it very basically, cochlear implants detect noises via an external head-mounted microphone, then stimulate the user's auditory nerve so that the hearing center of their brain can register those sounds. When such devices are initially being calibrated, the patient guides the clinician by telling them how well the implant is currently allowing them to hear.
The problem is, people such as small children or dementia sufferers may not understand what's being asked of them, or they may not be able to express themselves clearly. If it were possible to read their brain waves when test sounds were being made, however, it might be possible to objectively determine how well they were hearing those noises.
Last year, scientists at Belgium's KU Leuven university were able to detect such hearing-related brain waves in volunteers wearing an electrode-equipped skull cap. It would be much better, however, if the implant itself could do the job … and now the researchers have developed one that does.
"A cochlear implant contains electrodes that stimulate the auditory nerve," says postdoctoral researcher Ben Somers. "We have succeeded in using these implanted electrodes to record the brain waves that arise in response to sound. That is a first. An additional advantage is that by carefully choosing the right measuring electrodes, we can measure larger brain responses than the classical EEG [electroencephalogram] with electrodes on the head."
Forgoing the electrode cap means that patients wouldn't have to be tested in a clinical setting, and in fact could be evaluated over a period of several days while going about their daily routine. This would provide better readings for real-world use. It is even hoped that ultimately, such "smart" cochlear implants could automatically adjust themselves in response to the user's brain waves.
A paper on the research, which was conducted in partnership with implant manufacturer Cochlear, was recently published in the journal Scientific Reports.
Source: KU Leuven