Implanted hearing devices restore hearing for people with partial or total hearing loss, provided their auditory nerve is still intact. The most popular example is the so-called cochlear implant that contains an arrangement of electrodes implanted into the cochlear. A microphone receives acoustic signals that are processed by a speech processor and transmitted to the electrodes as stimulating signals. The electrodes stimulate the auditory nerve using electric pulses, thus bypassing the function of the missing sensory hair cells in the cochlea.
The majority of known cochlear implants use a constant pulse rate at all electrodes of the electrode arrangement. The pulse rate of the single electrodes in the cochlear implant therefore does not allow for a differentiation of sounds, as is common experience for people with normal hearing abilities, for example, when distinguishing voices from background noise.
As part of the excellence cluster "Hearing4all", the research team "Models for hearing devices" at the University of Oldenburg developed a signal processing strategy for implantable hearing systems in order to enable improved speech intelligibility. The invention is based on the fact that the auditory nerve encodes voiced sounds, e.g. vowels, different to unvoiced sounds, by so-called rate encoding. To mimic this, the invention selects the pulse frequency and the electrodes to be stimulated for voiced sounds differently than for unvoiced sounds, which means flexibly and signal-dependent. The idea was inspired by physiological studies of the normal auditory systems. In first trials, the inventors discovered that cochlear implant users were able to understand vowels better with this new coding strategy.
A further development of the invention is desired, for example, in form of cooperation with a manufacturer of cochlear implants and in the excellence cluster "Hearing4all".
The improved perception of voiced sounds leads to better speech intelligibility.
The invention has been initially developed for cochlear implants; however, it may also be applicable to other types of implanted hearing devices, for example, brain-stem implants.
Frequency-specific stimulation rates, flexible variation of electrode allocation, natural hearing
DE 10 2016 214745.5, registered
Licensing, sales, cooperation and further development
Carl von Ossietzky University Oldenburg and Cluster of Excellence Hearing4all