The physical limits of active noise control of open windows

Abstract

Active noise control (ANC) is a potential technique to mitigate environmental noise through open windows of dwellings, leaving a small visual footprint (as opposed to passive barriers). Existing studies on ANC of open windows have shown that noise attenuate (up to 10 dB) is attainable under certain scenarios. The physical limits of this technique, however, are not clearly defined. Does ANC of open windows result in effective noise control in the whole room? How many anti-noise sources are needed to achieve satisfactory attenuation? How does the separation distance between anti-noise sources affect attenuation? To answer these questions, the physical limits of ANC of open windows have been investigated using finite element modelling in two dimensions. Various numbers of secondary sources are positioned in the plane of the window and optimised to minimise the sound power transmitted through the window due to an incident plane wave. Our simulations show that global control of noise is possible with ANC of open windows at low frequencies, regardless of noise incidence angles. By plotting the relationship between maximum attenuation as a function of the wavenumber, k, and window width, w, (i.e. attenuation against kw) for different angles of incidence, the optimised number of secondary sources (for different window sizes) can be decided based on the required level of attenuation

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ORCID for Jordan Cheer: orcid.org/0000-0002-0552-5506

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