traffic noise modeling and mitigation. The purpose of this study is to develop a practical truck noise source localization technique using acoustic beam-forming. An experimental 70+ microphone elliptical array was designed and fabricated for truck testing. Beam-forming software was developed and implemented using a computerized data acquisition system. Proof-of-concept tests were performed at low-speed and high-speed truck testing facilities for a representative sample of trucks with widely different characteristics to validate the measurement system performance. The measurement system design parameters were verified experimentally, and certain improvements to the system were recommended for future implementation based on the field experience. The developed beam-forming measurement system provided adequate noise mapping and localization for various noise sources on trucks, stationary and moving with the speed up to 50 mph. The results of the proof-of-concept testing presented in an accompanying paper (Part 2) confirm that the developed microphone array, data acquisition system and beam-forming software performed generally as expected and required no major adjustments.

Acoustics 08 Paris 1875The elliptical array whose development and insitu calibration has been discussed in Part I was deployed roadside a test track for measurement of passby truck noise. This paper is a discussion of the capability of that array to localize the sound sources on the truck and to quantify the source levels thus allowing rank-ordering of the sources. The paper discusses an effort to benchmark the array-based measurements against intensity measurements on an idling stationary truck and the use of the array's output to define clearly the vertical distribution of sources at frequencies in excess of about 250 Hz at vehicle speeds up to 80 km/h (50 mph).

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