A MEMS Condenser Microphone Based Acoustic Receiver for Intracochlear Sound Pressure Measurements

Background

The measurement of intracochlear sound pressure (ICSP) is an important objective method to evaluate the biomechanical process of hearing.

Objective:

The goal of this work is to demonstrate the feasibility and validation of an intracochlear acoustic receiver (ICAR) fulfilling all requirements for ICSP measurements in human temporal bones and in acute large animal experiments. In addition, the ICAR concept is designed to be used in future chronic animal experiments and for an implantable microphone for totally implantable cochlear implant systems (TICI).

Methods:

The ICAS concept is based on a commercially available MEMS condenser microphone customized with a protective diaphragm that provides sealing and optimized geometry for accessing the tiny fluid-filled inner ear. The ICAR are calibrated and used to measure ICSP in the scala tympani of human and sheep temporal bones and for acute experiments in sheep at high acoustic stimulation levels.

Results

The ICSP measurements in human cadaver temporal bones yielded data in agreement with the literature. Acute ICSP measurements in sheep were successfully performed and surgeons who performed the ICAR insertion reported consistently high levels of ease of use and satisfaction with the system design.

Conclusions

Our results confirm that the developed ICAR can be used to measure ICSP in temporal bones and in acute large animal experiments. Currently, the development of a fully biocompatible ICAR for chronic experiments is ongoing. This future sensor design must fulfill all important requirements of a TICI device such as high performance, low power consumption and good system integration.