Piezoelectric MEMS microphones for hearing aids

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 percent [Marke, (2010)] 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 application, 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-electro- mechanical system (MEMS) microphones that satisfy the stringent acoustical specifications of the hearing aid industry will be undertaken. The two specific aims of the grant are to (1) design and fabricate the MEMS piezoelectric transducer element (2) design and implement the amplifying electronics for readout of the transducer's electrical signal that meet the requirements for HA applications. The technological feasibility will be determined by acoustic and electrical testing of the microphone. 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, ease integration with packaging and processing microelectronics, 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 (e.g., for noise cancelation) as well as those that may require close integration with downstream circuitry, such might be needed for self-fitting HAs. PUBLIC HEALTH RELEVANCE: Even though roughly 30 million Americans suffer from hearing loss and would benefit from some form of hearing augmentation the hearing aid (HA) adoption rate is less than 25 percent [Marke, (2010)]. In this application, a new class of HA microphones is to be developed that will reduce their cost and enable new types of HAs to be developed. Increased utilization of more effective HAs would help those who suffer from hearing impairment by improving their quality of life and productivity through better treatment.