Funding tool: Basic research projects
Project-ID: LS14-026
Project start: 01. November 2015
Project end: will follow
Runtime: 36 months / finished
Funding amount: € 309.360,00

Brief summary:

Implantable hearing aids are in clinical use since more than 25 years. These include cochlear implants (CI), auditory brainstem implants (ABIs), bone-anchored hearing aids (BAHA) and implantable middle-ear implants (MEI). The main challenge for all these implantable devices is a lack of reliability of the implantable microphone due to a constant decrease of the initial sensitivity after exploitation. In this project we propose a contactless fiber-optic sensing technique based on low-coherence interferometry for amplitude measurement of the hearing ossicles, e.g. incus or malleus. Our approach is physiologically fully justified because sound transmission to the inner ear can be realized without any obstacles, taking advantage of the natural amplification properties of the outer ear and the ear drum. There is no feedback noise and signal distortion due to decoupling the microphone from the actuator. The contactless method does not change the original properties of the acoustic signal at all and the ossicle chain stays intact. The distance of about 5 mm between the sensing fiber and ossicle is large enough to prevent scarring. This also allows to use the device in case of small quasi-static long-term movements of ossicle in the middle-ear, that usually occur during the children growth, or rather large quasi-static short-term movements in case of alternation of atmospheric pressure or chewing. The current prototype of the device can reach sensitivity of about 40db SPL and about 70db SPL in audio frequency range which now should be further improved to around 30 dB SPL by increasing the signal-to-noise-ratio (SNR) of the system, accomplished by noise suppression of some individual parts of the system, like light source, fiber-optic link, photo receiver, or overall sensing configuration. Additionally, a more effective algorithm will be developed and embedded in a low-consumption DSP. The results will be verified by pre-clinical ex-vivo examination

Keywords:
otolaryngology