Development of MEMS microphone array technology for aeroacoustic testing

• Published in: The Journal of the Acoustical Society of America 2004-10, Vol.116 (4_Supplement), p.2511-2511
• Main Authors: Shams, Qamar A., Graves, Sharon S., Bartram, Scott M., Sealey, Bradley S., Comeaux, Toby
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4785018

A new approach to aeroacoustic microphone array design and implementation is described and demonstrated. Using commercially available, low-cost MEMS microphones exhibiting a suitable low-frequency response, a series of 128-channel arrays were constructed on flexible Kapton circuit boards which were bonded to rigid aluminum backplates. Cover panels with precision cutouts for the microphones were bonded on top of the Kapton circuit boards to create a smooth surface providing flush-mounting for all microphones. Connections for the microphones were created by extending strips of Kapton containing power and signal busses to the rear of the backplates. All channels were powered from a common 3 V power source, and all signals were conditioned using custom-manufactured filtering and line-driving hardware. The conditioned signals were digitized and processed in near real-time using both commercially available and customized data acquisition and analysis hardware. This new type of array construction addresses two challenges which currently limit the widespread use of large channel-count arrays for aeroacoustic applications, namely by providing a lower cost-per-channel solution and by providing a simpler method for mounting microphones in wind tunnels. The MEMS arrays have been extensively tested in anechoic and hard-walled facilities, and their performance has been found comparable to that of condenser microphone arrays.