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A criterion based on the calculation of a solid angle to assess the quality of acoustic images obtained with a SMA


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Rouard, Kevin, St-Jacques, Julien, Sgard, Franck, Doutres, Olivier, Nélisse, Hugues, Boileau, Loic, Berry, Alain, Quaegebeur, Nicolas, Grondin, François and Padois, Thomas. 2023. « A criterion based on the calculation of a solid angle to assess the quality of acoustic images obtained with a SMA ». [Conference paper]. Canadian Acoustics = Acoustique Canadienne, vol. 51, nº 3. pp. 178-179.

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The quality of an acoustic image is evaluated based on criteria such as the source level, the mainlobe-to-sidelobes ratio and the spatial resolution. Spatial resolution can be evaluated by the mainlobe area. For spherical microphone arrays, polar projection and ellipse area can be used. These methods are however applied in a plane and not in a spherical plane. In particular, the covariance ellipsemethod may exceed the spherical coordinate frame of the acoustic image when the mainlobe is large, typically at low frequencies, or when there are numerous sidelobes at high frequencies. In addition, the mainlobe may not be centered in the acoustic image and may be distorted around the poles. In order to overcome these limitations, a criterion based on the solid angle is introduced in this paper.The performance of the method based on the solid angle computation is compared with that based on the ellipse. Numerical simulations are performed using a spherical microphone array with a rigid t-design geometry, and spherical harmonics are used to generate the acoustic images. The results show that the solid angle method provides a more stable value compared to the covariance ellipse method when the source is not centered. When the source is centered, the results are similar except when sidelobes occur. In conclusion, the solid angle method provides a robust approach for evaluating the spatial resolution of acoustic images obtained with spherical microphone arrays.

Item Type: Peer reviewed article published in a journal
Additional Information: Thématique: Acoustics Week in Canada 2023. Montreal, QC, Canada. Oct. 03-06, 2023.
Doutres, Olivier
Affiliation: Génie mécanique
Date Deposited: 08 Nov 2023 15:29
Last Modified: 11 Dec 2023 18:47

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