Piezoelectric MEMS microphones for hearing aids

Period of Performance: 07/01/2014 - 06/30/2015


Phase 2 SBIR

Recipient Firm

Baker-calling, Inc.
Ann Arbor, MI 48105
Principal Investigator


DESCRIPTION (provided by applicant): Roughly 30 million Americans suffer from hearing loss and would benefit from some form of hearing augmentation. However, the hearing aid (HA) adoption rate is low, less than 25% [Kochkin, (2009)] and those who do adopt wait more than 10 years before doing so [Donahue, (2010)]. There are a variety of reasons for the low utilization rate and long delay in adopting HAs including effectiveness, price, comfort, size, and cosmetic issues. Clearly there is a need to improve HAs so that those who suffer from hearing impairment can be more effectively helped to improve their quality of life and productivity through better treatment. In this proposal, the development of a new microphone for HA applications is sought as one avenue to improve HA effectiveness and increase utilization. In particular, development of the first piezoelectric, micro-electromechanical system (MEMS) microphones that satisfy the stringent acoustical specifications of the hearing aid industry will be undertaken. The three specific aims of the grant are to (1) design and fabricate the MEMS piezoelectric transducer element, (2) design and fabricate the amplifying electronics for readout of the transducer's electrical signal, and (3) design an appropriate housing for the mechanical and electrical elements that meets the requirements for HA applications. Compared to the existing electret condenser microphone (ECM) based technology that has dominated the field for many years, the new microphone will: be more robust to the external environment, stable over time, ease hearing aid assembly, and deliver superior acoustic performance at a smaller size. Because the MEMS fabrication applied to create this device is based on the same processes used in the semiconductor industry, once the design of these devices is perfected they can be made at low cost and easily integrated with processing electronics. Our ultimate goal is to develop a microphone that provides better acoustic performance than present HAs at a cost comparable to microphones used for cell phones. The availability of robust, stable, and miniature microphones will improve existing and facilitate the development of new HA systems that utilize multiple microphones for directional sensing and noise cancellation. The goal of this NIH SBIR is to build these microphone prototypes, which will serve as the basis for improved microphones for the hearing aid industry.