The Use of Acoustic-Intensity Scans for Sound Power Measurement and for Noise Source Identification in Surface Transportation Vehicles

The results are reported of near-field, acoustic-intensity scans of a diesel-engine truck, chassis-mounted passenger-car engines, and a railroad locomotive. The measurements were made using the two-microphone, cross-spectral method of measuring acoustic intensity developed at General Motors. The results demonstrate the value of the method for measuring the overall sound power of a vehicle as well as for identifying its component noise sources. A review of theory and methodology is provided.