Multizone reproduction by matching the velocity vectors

Abstract

This paper proposes a velocity-based multizone reproduction method, which reproduces the velocity vectors throughout each listening zone. Velocity vectors are related to the localization of sound below 700 Hz. Previous work considered reproducing the velocity vectors at sweet spots or on the listening zone’s boundary, and usually involved measurements using multiple velocity sensors. In this paper, in each listening zone, the velocity vectors are calculated from the spherical harmonic coefficients of the pressure, which are obtained by a spherical microphone array. The calculation of the velocity vectors is based on the sound field translation formula. Moreover, by reproducing the desired velocity vectors throughout each listening zone, listener's movement within each zone is allowed. To enlarge the size of the listening zone, the sound field in each listening zone is expressed by a sparse distribution of plane waves that results in the same velocity vectors. The pressure transfer functions between each loudspeaker and each listening zone are measured by placing a spherical microphone array at multiple spatial sampling points within each listening zone. The loudspeaker driving functions are calculated by matching the velocity vectors due to the sparse distribution of plane waves in each listening zone.