Two-dimensional DOA (direction of arrival) estimation for low frequency sound sources with vector acoustic intensity array

The acoustic intensity is a vector pointing in the direction of net power flow and can therefore be used to locate sound sources. We design a holder for the vector acoustic intensity array, which holds 3 pairs of microphones as three orthogonal dipoles to measure three components of the acoustic intensity simultaneously using the cross-spectrum method. The 2-dimensional DOA (Direction of Arrival) of the sound source, including the pitch and azimuth angles, is estimated with the three acoustic intensity components. Dimension of the array is 0.2 meter, much smaller than that of the widely used linear array of pressure sensors when determining the bearings of low frequency sound sources. We also analyze the systematic error and stochastic error of DOA estimation with the vector acoustic intensity array, and their contributions to the experimental results. Analysis of experimental results show that the 2-dimensional DOA of a sound source radiating noise of hundreds Hz may be estimated with satisfying precision by using the vector acoustic intensity array placed on a small platform of only 0.2 meter's dimensions.