MEMS Microphone Array

Tufts University
posted on 09/02/2011

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Tufts University Categories:
engineering:aerospace
semiconductor:MEMs
sensors

Additional Keywords:
(none specified)

Invention Summary

Background: As aircraft noise regulations become more stringent, the need for modeling and measuring aircraft noise phenomena becomes more important. In order to intelligently design quieter aircraft, the physical mechanisms of noise generation should be understood and any theoretical or computational noise model should be experimentally validated. One validation method is the comparison of the theoretical and measured acoustic far-field pressures. However, single microphone measurements of aeroacoustic sources in wind tunnels are hampered by poor signal to noise ratios that arise from microphone wind self-noise, tunnel system drive noise, reverberation, and electromagnetic interference. In addition, a single microphone cannot distinguish pressure contributions from different source locations. The need for more precise noise source characterization and localization has driven the development of advanced sound field measurement techniques. In particular, the development and application of directional (phased) microphone arrays have been documented as a means to localize and characterize aeroacoustic sources in the presence of high background noise. Invention: The sensor covered by this invention is novel due to the use of a fully surface micromachined foundry process, a microphone array on a single chip with a fine center-to-center pitch, and front venting. The pressure sensor array has a center-to-center pitch of 1.2625 mm with a membrane diameter of 600 microns (shown in Figure 4). Due to this the sensor will be able to provide high resolution data on the frequency wavenumber spectra of the TBL experienced by an aircraft in flight. Also, by assembling the array chips end-to-end, this sensor will be able to determine low wavenumber information through the larger spatial scale.