Signal-Adaptive and Perceptually Optimized Sound Zones with Variable Span Trade-Off Filters

TL;DR

This paper introduces a novel sound zone control method that optimizes leakage error audibility by considering human perception and input signal characteristics, achieving higher contrast and perceptual quality than existing methods.

Contribution

It proposes variable span trade-off filters that shape leakage errors based on auditory perception and signal properties, improving sound zone control performance.

Findings

Achieves over 20% perceptual improvement in listening tests.

Provides more than 15 dB acoustic contrast in practical setups.

Demonstrates the effectiveness of perceptually optimized leakage shaping.

Abstract

Creating sound zones has been an active research field since the idea was first proposed. So far, most sound zone control methods rely on either an optimization of physical metrics such as acoustic contrast and signal distortion or a mode decomposition of the desired sound field. By using these types of methods, approximately 15 dB of acoustic contrast between the reproduced sound field in the target zone and its leakage to other zone(s) has been reported in practical set-ups, but this is typically not high enough to satisfy the people inside the zones. In this paper, we propose a sound zone control method shaping the leakage errors so that they are as inaudible as possible for a given acoustic contrast. The shaping of the leakage errors is performed by taking the time-varying input signal characteristics and the human auditory system into account when the loudspeaker control filters are calculated. We show how this shaping can be performed using variable span trade-off filters, and we show theoretically how these filters can be used for trading signal distortion in the target zone for acoustic contrast. The proposed method is evaluated based on physical metrics such as acoustic contrast and perceptual metrics such as STOI. The computational complexity and processing time of the proposed method for different system set-ups are also investigated. Lastly, the results of a MUSHRA listening test are reported. The test results show that the proposed method provides more than 20% perceptual improvement compared to existing sound zone control methods.