An experimental study on transfer function estimation using acoustic modelling and singular value decomposition

Transfer functions relating sound source strengths and the sound pressure at field points areimportant for sound field control. Recently, two modal domain methods for transfer functionestimation have been compared using numerical simulations. One is the spatial harmonicdecomposition (SHD) method, which models a sound field with a series of cylindrical waves;while the other is the singular value decomposition (SVD) method, which uses prior sound sourcelocation information to build an acoustic model and obtain basis functions for sound fieldmodelling. In this paper, the feasibility of the SVD method using limited measurements to estimatetransfer functions over densely-spaced field samples within a target region is demonstratedexperimentally. Experimental results with various microphone placements and systemconfigurations are reported to demonstrate the geometric flexibility of the SVD method comparedto the SHD method. It is shown that the SVD method can estimate broadband transfer functionsup to 3099 Hz for a target region with a radius of 0.083 m using three microphones, and allowflexibility in system geometry. Furthermore, an application example of acoustic contrast control ispresented, showing that the proposed method is a promising approach to facilitating broadbandsound zone control with limited microphones