Portable 512 MEMS-Microphone-Array for 3D-Intensity- and Beamforming-Measurements using a FPGA based Data-Acquisition-System

Abstract

In this paper a portable MEMS-Microphone-Array with integrated Data-Acquisition-System is presented. 512 digital MEMS-Microphones are located in a rectangular box of 17 x 15 x 20 cm. The microphone positions are chosen for sound intensity measurements, but are capable of beamforming as well. Depending on the frequency, these microphones can be used as an array of hundreds of 3D - intensity probes. The acoustic velocity is estimated using a high order three dimensional finite difference stencil to overcome the upper frequency limit of common pp-intensity probes. At low frequencies, pairs with larger spacing are used to reduce the requirement of accurate phase match of the microphone sensors. Additionally a procedure is shown for amplitude and phase calibration of MEMS-Sensors. All microphone data is collected by an FPGA and send via the UDP-Protocol to any host system for beamforming and intensity calculations in real time or for storing the data to disk.