Sound Zone Control Robust To Sound Speed Change

TL;DR

This paper introduces SICER, a method to correct impulse responses for sound speed variations in sound zone control, enhancing robustness without re-measuring IRs, and integrates it with VAST for improved performance.

Contribution

The paper presents SICER, a novel IR correction technique for sound speed changes, combined with VAST, to improve SZC robustness against environmental perturbations.

Findings

Significantly improves acoustic contrast under sound speed variations

Reduces signal distortion caused by temperature and humidity changes

Eliminates need for re-measuring IRs when environmental conditions change

Abstract

Sound zone control (SZC) implemented using static optimal filters is significantly affected by various perturbations in the acoustic environment, an important one being the fluctuation in the speed of sound, which is in turn influenced by changes in temperature and humidity (TH). This issue arises because control algorithms typically use pre-recorded, static impulse responses (IRs) to design the optimal control filters. The IRs, however, may change with time due to TH changes, which renders the derived control filters to become non-optimal. To address this challenge, we propose a straightforward model called sinc interpolation-compression/expansion-resampling (SICER), which adjusts the IRs to account for both sound speed reduction and increase. Using the proposed technique, IRs measured at a certain TH can be corrected for any TH change and control filters can be re-derived without the need of re-measuring the new IRs (which is impractical when SZC is deployed). We integrate the proposed SICER IR correction method with the recently introduced variable span trade-off (VAST) framework for SZC, and propose a SICER-corrected VAST method that is resilient to sound speed variations. Simulation studies show that the proposed SICER-corrected VAST approach significantly improves acoustic contrast and reduces signal distortion in the presence of sound speed changes.