The influence of scattering on the directivity of spherical microphone arrays
The influence of scattering on the directivity of spherical microphone arrays
The aim of this research is to examine the properties of a microphone array on a rigid sphere that could be used for teleconferences and for the live recording of music. Computer simulations undertaken, within a MATLAB environment, have been used to evaluate the directivity of circular microphone arrays. The beamformer used in the study is a "focused beamformer" that attempts to map the distribution of acoustic source strength associated with a given source distribution by changing the Green function vector in accordance with the assumed source position. The scattering of sound by a rigid sphere was studied in order to understand its effects on the directivity of the array. It has been shown previously that a microphone array on a rigid sphere has better directivity than the same microphone array in a free field [1, 2, 3]. Similar results are produced by two systems of microphones: one on a rigid sphere and the other in the free field that had as diameter half of the circumference of the rigid sphere. Since the results obtained for low frequencies were similar, the size of the sphere seems to be the main factor affecting directivity at low frequencies. The presence of a rigid sphere increases the path length traveled by incident sound that simply passes through a microphone array in a free field. In addition, the creeping waves formed on the surface of the sphere have a lower phase velocity than the sound speed. The velocity of the creeping waves also increases with frequency. These observations help to explain the enhanced directivity of the rigid sphere microphone array.
4238-4245
International Institute of Acoustics and Vibration
Cardoso, Clara Ferreira
264880a7-4976-471c-a131-4deedd1b2072
Nelson, Philip
5c6f5cc9-ea52-4fe2-9edf-05d696b0c1a9
2005
Cardoso, Clara Ferreira
264880a7-4976-471c-a131-4deedd1b2072
Nelson, Philip
5c6f5cc9-ea52-4fe2-9edf-05d696b0c1a9
Cardoso, Clara Ferreira and Nelson, Philip
(2005)
The influence of scattering on the directivity of spherical microphone arrays.
In 12th International Congress on Sound and Vibration 2005, ICSV 2005.
vol. 5,
International Institute of Acoustics and Vibration.
.
Record type:
Conference or Workshop Item
(Paper)
Abstract
The aim of this research is to examine the properties of a microphone array on a rigid sphere that could be used for teleconferences and for the live recording of music. Computer simulations undertaken, within a MATLAB environment, have been used to evaluate the directivity of circular microphone arrays. The beamformer used in the study is a "focused beamformer" that attempts to map the distribution of acoustic source strength associated with a given source distribution by changing the Green function vector in accordance with the assumed source position. The scattering of sound by a rigid sphere was studied in order to understand its effects on the directivity of the array. It has been shown previously that a microphone array on a rigid sphere has better directivity than the same microphone array in a free field [1, 2, 3]. Similar results are produced by two systems of microphones: one on a rigid sphere and the other in the free field that had as diameter half of the circumference of the rigid sphere. Since the results obtained for low frequencies were similar, the size of the sphere seems to be the main factor affecting directivity at low frequencies. The presence of a rigid sphere increases the path length traveled by incident sound that simply passes through a microphone array in a free field. In addition, the creeping waves formed on the surface of the sphere have a lower phase velocity than the sound speed. The velocity of the creeping waves also increases with frequency. These observations help to explain the enhanced directivity of the rigid sphere microphone array.
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Published date: 2005
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Copyright 2013 Elsevier B.V., All rights reserved.
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12th International Congress on Sound and Vibration 2005, ICSV 2005, , Lisbon, Portugal, 2005-07-11 - 2005-07-14
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Local EPrints ID: 468701
URI: http://eprints.soton.ac.uk/id/eprint/468701
PURE UUID: b738f95a-cd26-4d68-93cd-b9277c3de37e
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Date deposited: 23 Aug 2022 16:45
Last modified: 07 Mar 2024 02:33
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Author:
Clara Ferreira Cardoso
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