Oldenburg. A new development in the area of electroencephalogram measurements: electroencephalograms (EEG) can be used to measure and interpret brain waves. Scientists from the cluster of excellence Hearing4all succeeded in developing a new cap for a highly complex state-of-the-art measuring method. The cap simplifies the handling during scientific measurements with patients with inner ear implants - the so-called cochlear implants - and helps to improve the results.

EEG measurements are widely used in hearing science. Scientists hope to gather new insight into the processing during listening and understanding using EEG. During EEG measurements with normal-hearing people a bathing cap-like headpiece with sensitive measuring electrodes is used. When trying to do measurements with severely hearing-impaired or deaf people with a cochlear implant, one however encounters technical difficulties. In cochlear implants, acoustic signals are recorded outside the ear, converted into an electrical signal and then transmitted to electrodes located inside the ear. This is done using a coil located on the head right behind the ear. Unfortunately, this coil may shift during the measurements with conventional EEG caps and may lead to imprecise measurement results. Often, the cap causes the coil to put an uncomfortable pressure onto the skullcap. The cable of the coil which also runs underneath the measurement cap can affect the electrodes. Furthermore, during the complex preparations for the EEG measurements, the test persons are required to put on a research coil which impairs their hearing; they are practically deaf in the experimental setup.

The new EEG cap which was developed by Dr. Mathias Dietz, junior research group leader in the Medical Physics group, and his team in cooperation with the Easycap GmbH offers a workaround. The scientists designed a cap which has an opening for the coil of the cochlear implant and which does not affect the highly sensitive electrodes. The test persons can use their implant and operate the coil during the measurements. "Compared to conventional EEG caps, the new model is more flexibly applicable", reports Dietz. The novel cap allows for a more comfortable and simple scientific operation and offers noticeably more comfort to the test subject. Dietz and his team use the new cap in their research to improve the tuning between the left and right cochlear implant and to facilitate the binaural hearing - meaning the simultaneous signal processing with both ears.

The new cap can also be used in a similar way to audiologically fine-tune conventional monaural cochlear implants. In order to attune a cochlear implant specifically to a person, many sessions with an audiologist are required. "EEG measurements with the new cap may help to improve the fine-tuning of cochlear implants," says Dietz. Especially with small children who cannot communicate with the audiologist the cap could simplify the adjustment drastically.