Sound Zones As An Optimal Filtering Problem

The design of so-called sound zones is a fairly old idea which has recently gained some research attention. The idea is to control a loudspeaker array to reproduce a desired sound field in certain regions. In this paper, we show how the sound zone control problem can be solved using techniques from speech enhancement. Specifically, we first describe in detail the recently introduced variable span linear filtering (VSLF) framework which unifies the popular optimal filtering and subspace-based approaches to speech enhancement. We then show how the sound zone control problem can be solved using the VSLF framework and how a number of well-known sound zone control methods can be viewed as special cases of this solution. We also discuss in detail the differences between the speech enhancement problem and the sound zone control problem and argue that the VSLF framework is actually even better suited for controlling sound zones than for enhancing speech.