A directional acoustic array using silicon micromachined piezoresistive microphones.

The need for noise source localization and characterization has driven the development of advanced sound field measurement techniques using microphone arrays. Unfortunately, the cost and complexity of these systems currently limit their widespread use. Directional acoustic arrays are commonly used in wind tunnel studies of aeroacoustic sources and may consist of hundreds of condenser microphones. A microelectromechanical system (MEMS)-based directional acoustic array system is presented to demonstrate key technologies to reduce the cost, increase the mobility, and improve the data processing efficiency versus conventional systems. The system uses 16 hybrid-packaged MEMS silicon piezoresistive microphones that are mounted to a printed circuit board. In addition, a high-speed signal processing system was employed to generate the array response in near real time. Dynamic calibrations of the microphone sensor modules indicate an average sensitivity of 831 microV/Pa with matched magnitude (+/-0.6 dB) and phase (+/-1 degree) responses between devices. The array system was characterized in an anechoic chamber using a monopole source as a function of frequency, sound pressure level, and source location. The performance of the MEMS-based array is comparable to conventional array systems and also benefits from significant cost savings.

[1]  Marianne Mosher,et al.  The microphone array phased processing system (MAPPS) , 1996 .

[2]  Srba Jovic,et al.  CALIBRATION OF MICROPHONE ARRAYS FOR PHASED ARRAY PROCESSING , 1997 .

[3]  Paul T. Soderman,et al.  A directional microphone array for acoustic studies of wind tunnel models , 1975 .

[4]  R. Kinns,et al.  The acoustic telescope , 1976 .

[5]  Marianne Mosher.  Phased arrays for aeroacoustic testing - Theoretical development , 1996 .

[6]  Renaud Davy,et al.  AIRFRAME NOISE CHARACTERISTICS OF A 1/11 SCALE AIRBUS MODEL , 1998 .

[7]  Jr William M. Humphreys,et al.  Design and Use of Microphone Directional Arrays for Aeroacoustic Measurements , 1998 .

[8]  Jr William M. Humphreys,et al.  Effect of Directional Array Size on the Measurement of Airframe Noise Components , 1999 .

[9]  Georges Elias,et al.  AIRFRAME NOISE SOURCE LOCALIZATION USING A MICROPHONE ARRAY , 1997 .

[10]  J. Bendat,et al.  Random Data: Analysis and Measurement Procedures , 1971 .

[11]  T Kegelman Jerome.  Accelerating Ground-Test Cycle Time: The Six-Minute Model Change and Other Visions for the 21st Century , 1998 .

[12]  Pieter Sijtsma,et al.  Source Location by Phased Array Measurements in Closed Wind Tunnel Test Sections , 1999 .

[13]  Thomas F. Brooks,et al.  A directional array approach for the measurement of rotor noise source distributions with controlled spatial resolution , 1987 .

[14]  Rahul Sen,et al.  An experimental investigation of airframe noise using a model-scale Boeing 777 , 2001 .