Acoustic dyadic sensor's correlation in ambient noise fields

An acoustic dyadic sensor can be used to measure pressure, particle velocity and velocity gradient at a single point in space. The obtained information is very useful for improving detection and estimation of a sonar. Here, the auto-correlation of velocity gradient, the cross-correlation between pressure and velocity gradient, and that between particle velocity and velocity gradient in a 3-D spherical isotropic noise field were investigated. Noise covariance matrix was derived, and a simple simulation method of an isotropic noise field was analyzed. The numerical simulation results utilizing this method agreed well with the theoretical values. It was indicated that the theory and the simulation method proposed are effective.