Health Spain , Salamanca, Thursday, May 09 of 2013, 10:49

Objective tests to assess hearing impairments

Spanish scientists have conducted the study for an American company and now they are improving the technique. Main goal: tailored hearing aid.

José Pichel Andrés/DICYT Thanks to the funding granted by an American company called Starkey, the Instituto de Neurociencias de Castilla y León (INCYL), an institute of neuroscience at the Universidad de Salamanca , has performed tests, during two years, with patients suffering from bilateral sensorineural hearing loss, a common hearing impairment in older people. The ultimate goal is to understand why a hearing-aid device is more effective in some patients than in other with the same hearing problem. This new project aims to make tests faster and more objective measuring brain activity with electrodes. Instead of having many consultations during months, a few minutes will be enough to carefully explore patients.

In this study for Starkey, scientists have assessed about 400 patients, and eventually studied 68 of them in detail. "We are starting to analyze data: a year and a half or two year process until we would be able to analyze and publish findings," as DiCYT was told by Enrique López Poveda, researcher at Incyl and head of this research area.

Each of the patients had to undergo tests during a month, two hours every day, and subsequent monitoring consultations for another two months, that is, the process was very long and required a lot of dedication from volunteer patients. "It seemed impossible, but we achieved what we wanted and everything went well," the expert states. They performed auditory perception and otoacustic emission tests: stimulating hearing with sounds and analyzing its echo.

Researchers' hypothesis is that some patients suffer from greater damages in inner hair cells and others in outer hair cells. The first ones pick up sounds and the second ones amplify them, but when hearing damage occurs, it is impossible to know which ones are affected. "We have collected many indicators of potential damage in inner and outer hair cells. But these are indirect indicators based on perception tests and must be validated," López Podeva explains. Consequently, a new national research project will try to do so objectively. Using patients’ information, tailored hearing-aid devices can be made.

Although scientists rely on the fact that, sure enough, indicators used in tests are providing information on damages in each type of cell, they want to develop an objective clinical technique to perform measures in hospital settings. "Instead of performing tests during a month, we could do the same during a few minutes, or during an hour at most," the researcher states.

Instead of auditory perception and otoacustic emission tests, this technique is performed by placing electrodes on the scalp and measuring electrical brain activity responding to acoustic stimuli. "When you place electrodes on the temporal bone, you are measuring electrical potential by auditory neurons," a faster and more objective test to continue the technology building that in the near future could allow the development of hearing aid devices taking into account this new information.

A University Service for Patients

Besides the research’s chief aim, scientists have proved that there are many patients dissatisfied with the service provided by hearing aid departments. "Many people participating in the study demand external hearing aids and audiology services by universities," López Poveda states. "Most of them participated because they wanted higher quality and less expensive services," he adds.

That is the reason why López Poveda has suggested to the Universidad de Salamanca the creation of an audiology external service, only requiring "a couple of offices". Therefore, his work on this area would be completed, not only in research and in relationships with companies, but also in training process, since the Certificate in Audiology taught by Incyl is a national benchmark diploma, and a service like this would be perfect for students’ working-experience.