Determining 3-D acoustic intensity from 2-D probes

Acoustic intensity measurements are a useful method for determining the location of a complex acoustic source such as a rocket. However, field probes for measuring acoustic intensity may need to be placed on the ground to reduce the effects of ground reflections. Since it would be useful to obtain three-dimensional intensity from a two-dimensional probe, a new approach for processing acoustic intensity is being investigated. Two components of the acoustic intensity in the plane of the probe are calculated using the PAGE method [Thomas et al. J. Acoust. Soc. Am. 137 (2015)]. Using theaverage pressure recorded by the microphones, the total magnitude of the acoustic intensity can be estimated and used with the two components already determined to solve for the third component. To test this method of obtaining the 3-D intensity from a 2-D probe a controlled experiment was designed. Intensity probes were set up in a field with no large obstructing structures nearby and a manlift was used to place a loudspeaker at various known positions from the probes. At each position, recordings were obtained of white noise and chirp signals. Using the data collected in this controlled environment, the efficacy of this method of obtaining the acoustic intensity is assessed.