Tonal active control of the power scattered by locally-reacting spheres using a small number of radiators near the surface: active control of scattering
Tonal active control of the power scattered by locally-reacting spheres using a small number of radiators near the surface: active control of scattering
A theoretical investigation is performed where spherical harmonic series expansions are used to describe the primary and secondary pressure fields in the problem of actively controlling sound scattering around spheres. The study focuses on the scenario of point-monopoles radiators in the vicinity of a sphere with a uniform, locally-reacting and real-valued surface impedance. A control method based on minimizing the contributions of the spherical harmonic components to the scattered sound power is proposed. Under the established circumstances, any radiated sound power is found to be dominated by a few spherical harmonic terms of low degree in the region of large relative wavelength. As this wavelength decreases, numerous terms of higher degree become significant, thus increasingly more sources are required to achieve any suppression. A study case is performed where one point-monopole is placed at infinite distance to form an incident plane-wave. The scattering due to this is controlled with up to four point-monopoles on or near the surface of the sphere. Progressively better attenuation is achieved at large relative wavelength when increasing the number of control sources and the behavior can be described using asymptotes of the spherical harmonic coefficients.
active control of sound, 3D sound scattering, spherical harmonics, locally-reactiong sphere, impedance sphere, plane-wave scattering
69-76
Deutsche Gesellschaft für Akustik
Oriță, Mihai
b5850bb4-8337-4865-bb8f-50860169bee0
Elliott, Stephen
721dc55c-8c3e-4895-b9c4-82f62abd3567
Cheer, Jordan
8e452f50-4c7d-4d4e-913a-34015e99b9dc
9 September 2019
Oriță, Mihai
b5850bb4-8337-4865-bb8f-50860169bee0
Elliott, Stephen
721dc55c-8c3e-4895-b9c4-82f62abd3567
Cheer, Jordan
8e452f50-4c7d-4d4e-913a-34015e99b9dc
Oriță, Mihai, Elliott, Stephen and Cheer, Jordan
(2019)
Tonal active control of the power scattered by locally-reacting spheres using a small number of radiators near the surface: active control of scattering.
In Proceedings of the 23rd International Congress on Acoustics, integrating 4th EAA Euroregio 2019: Session 01 A - Physical aspects for active control of noise and vibration.
Deutsche Gesellschaft für Akustik.
.
Record type:
Conference or Workshop Item
(Paper)
Abstract
A theoretical investigation is performed where spherical harmonic series expansions are used to describe the primary and secondary pressure fields in the problem of actively controlling sound scattering around spheres. The study focuses on the scenario of point-monopoles radiators in the vicinity of a sphere with a uniform, locally-reacting and real-valued surface impedance. A control method based on minimizing the contributions of the spherical harmonic components to the scattered sound power is proposed. Under the established circumstances, any radiated sound power is found to be dominated by a few spherical harmonic terms of low degree in the region of large relative wavelength. As this wavelength decreases, numerous terms of higher degree become significant, thus increasingly more sources are required to achieve any suppression. A study case is performed where one point-monopole is placed at infinite distance to form an incident plane-wave. The scattering due to this is controlled with up to four point-monopoles on or near the surface of the sphere. Progressively better attenuation is achieved at large relative wavelength when increasing the number of control sources and the behavior can be described using asymptotes of the spherical harmonic coefficients.
Text
Tonal active control of the power scattered by locally-reactingspheres using a small number of radiators near the surface
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e-pub ahead of print date: 9 September 2019
Published date: 9 September 2019
Venue - Dates:
23rd International Congress on Acoustics, integrating 4th EAA Euroregio 2019, Eurogress Aachen, Aachen, Germany, 2019-09-09 - 2019-09-13
Keywords:
active control of sound, 3D sound scattering, spherical harmonics, locally-reactiong sphere, impedance sphere, plane-wave scattering
Identifiers
Local EPrints ID: 434320
URI: http://eprints.soton.ac.uk/id/eprint/434320
ISSN: 2226-7808
PURE UUID: 37395271-b4a0-4d4d-ad3a-d94d0eb271d0
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Date deposited: 19 Sep 2019 16:30
Last modified: 17 Mar 2024 03:22
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Author:
Mihai Oriță
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