Separation of nonstationary sound fields based on the time-domain equivalent source method with double-layer pressure measurements

This paper proposes a sound field separation technique based on the time-domain equivalent source method with double-layer pressure measurements. It aims to extract the nonstationary sound field radiated by the target source in a noisy environment. The technique establishes a formulation relating the pressures on two measurement surfaces to the strengths of time-domain equivalent sources that are arranged to model the outgoing and incoming waves. By resolving the strengths of these time-domain equivalent sources, sounds from different sides of the measurement surface can be separated independently. In the proposed technique, the application of the time-domain equivalent source model enables the measurement surfaces to be arbitrarily shaped. This provides the capability to analyze the arbitrarily shaped sources in a noisy environment. Numerical simulations examined the performance of the proposed technique using different types of arrays, such as planar, semi-cylindrical, and semi-spherical arrays. An experiment was conducted with two loudspeakers placed at two sides of the measurement surfaces, respectively, to verify the validity of the proposed technique. Both numerical and experimental results demonstrate that the proposed technique can eliminate the influence of disturbing sources in both time and space domains and effectively separate out the target sound fields.