In situ tuning of omnidirectional microelectromechanical-systems microphones to improve performance fit in hearing aids

Hearing aids are not a one-size-fits-all solution to hearing problems; they must be uniquely tuned for each wearer. There are currently no low-cost and/or effective methods for in situ tuning. This paper describes a microelectromechanical-systems MEMS -based dual omnidirectional microphone that can be tuned by growing metallic nanostructures. The nanostructures are grown on integrated solid electrolyte layers on a suspended parylene diaphragm using an external bias and tune the MEMS microphones in situ thereby limiting mismatch. In our tests, this tuning improved the directivity index from 3.5 fair directionality to 4.6 dB excellent directionality in normal room temperature operating environments. © 2008 American Institute of Physics. DOI: 10.1063/1.2989132