Automatic Measurement of Spatial Acoustic Intensity

A method of measuring acoustic intensity automatically is presented in this paper. The method uses measurements of the cross spectrum of the pressures at two closely spaced microphones. The two microphones used are arranged side by side with a short distance between their axes, and combined symmetrically with a holder axis. The holder can be turned on its axis by steps of a constant angle for measuring three directional components of an acoustic intensity vector. The acoustic intensity at a field point can be automatically measured by such composed microphones. This method is actually applied to a visualization technique of the flow pattern of sound energy emitted from a resonant modes. As a result, an acoustic intensity probe composed of two microphones, as used in this study, has been proved to be an apprepriate sensor for the automatic measurement of spatial acoustic intensity.