Exploiting the Underdetermined System in Multichannel Active Noise Control for Open Windows

Jianjun He,Bhan Lam,Woon Seng Gan,Dongyuan Shi

doi:10.3390/app9030390

Abstract

Active noise control (ANC) is a re-emerging technique to mitigate noise pollution. To reduce the noise power in large spaces, multiple channels are usually required, which complicates the implementation of ANC systems. In this paper, we separate the multichannel ANC problem into two subproblems, where the subproblem of computing the control filter is usually an underdetermined problem. Therefore, we could leverage the underdetermined system to simplify the ANC system without degrading the noise reduction performance. For a single incidence, we compare the conventional fully-coupled (pseudoinverse) multichannel control with the colocated (diagonal) control method and find that they can achieve equivalent performance, but the colocated control method is less computationally intensive. Furthermore, the underdetermined system presents an opportunity to control noise from multiple incidences with one common fixed filter. Both the full-rank and the overdetermined optimal control filters are realized. The performance of these control methods was analyzed numerically with the Finite Element Method (FEM) and the results validate the feasibility of the full-rank and overdetermined optimal control methods, where the latter could even offer more robust performance in more complex noise scenarios.

Highlights

Active noise control (ANC) mitigates disturbances by generating sound waves that interfere destructively with the primary noise field
In light of the increasing awareness of health risks associated with long-term exposure to environmental noise [7,8,9], sustainable noise mitigation methods need to be implemented to increase the aural comfort in affected urban accommodation
We study the theoretical performance with deterministic disturbances, unless otherwise mentioned [22]

Summary

Introduction

Active noise control (ANC) mitigates disturbances by generating sound waves that interfere destructively with the primary noise field. The destructively interfering sound field is generated by secondary sources driven to minimize the sum-of-squared pressures at the error microphone locations [1]. In light of the increasing awareness of health risks associated with long-term exposure to environmental noise [7,8,9], sustainable noise mitigation methods need to be implemented to increase the aural comfort in affected urban accommodation. Because windows are the main entry points for environmental noise in a building, active mitigation methods are most effective when targeted at such openings. ANC techniques that can mitigate noise through open windows are potentially sustainable solutions to environmental noise in tropical urban high-rise environments [10]

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Conclusion