Sound field control in a rectangular closed space using multiple selected room modes

Abstract

Sound field control using multiple loudspeakers is essential for many applications such as sound field reproduction for delivering an immersive sound experience and noise control. These sound field controls are generally required in closed spaces, such as living rooms or factories, where eigenmodes are prominent at low frequencies. Many studies on the control of a few modes in closed spaces have been conducted in the field of noise control. In this study, we attempted to reproduce arbitrary sound fields, such as plane and spherical waves, from virtual sound sources using simultaneous multiple eigenmodes based on room-mode matching (RMM). Because most rooms are generally considered rectangular at low frequencies, we expanded the target sound field with discrete cosine transform (DCT) by approximating the eigenmodes as cosine functions. We proposed a method for extracting the control modes necessary to reproduce the desired sound field considering the mode strength at a target frequency. The simulation results verified that the proposed method can reproduce propagating plane waves with loudspeaker arrays placed on both sides of the closed space while maintaining the loudspeaker filter gains at appropriate values.