Active control of scattering effects in 2.5D multizone reproduction

Multizone reproduction has gained significant interest in recent years for its advantage that listeners can enjoy their personal audio without physical isolation or wearing headphones. However, study of multizone reproduction has been focused on reproducing sounds in an empty listening space. The scattering effects of the human and objects in sound zones are often neglected, causing degraded system performance. In this work, we focus on reproduction on a 2D horizontal plane using 3D secondary sources, i.e., 2.5D reproduction. Through experiments we show how scatterers such as human head and body in sound zones influence reproduction results. A modal-domain method for 2.5D multizone reproduction with an active control strategy to correct the scattering effects is proposed. The method is based on modelling the human head as a rigid sphere, based on which analytical expressions are developed to represent the scattered sound field. The method is validated through experiments using a 48-element circular loudspeaker array. Experimental results especially show the improved acoustic contrast performance using the proposed method.