Sound-scattering properties of Sierpinski triangle fractal structures in the near field

Journal article (2022)

Authors

Lingge Tan Harbin Institute of Technology
Jieun Yang Eindhoven University of Technology
Jian Kang University College London
Hongpeng Xu Harbin Institute of Technology
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Diffusion coefficient Acoustic diffuser Sierpinski triangle
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Published Date

2022

Language

English

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Abstract

This paper proposes a new design of an acoustic diffuser based on the construction rules of the Sierpinski triangle in order to broaden the effective diffusion frequency range. The diffuser is made of triangular blocks of different sizes attached to a plane surface. The effects of the number of fractal iterations, the height of triangular blocks, and arrangements of the blocks on the normal-incidence diffusion coefficients in the near field are examined through numerical simulations based on the boundary element method (BEM) in the frequency range of 100 Hz – 5 kHz. Furthermore, measurement results will be presented to validate the diffusion performance presented by the numerical simulations. The diffusion performance of a conventional quadratic residue diffuser (QRD) is compared to confirm the advantage of the designed diffuser for broadening the effective frequency range. It shows that the fractal patterns with various sizes of blocks improve diffusion performance compared to the conventional QRD of the same size, especially in the mid-low frequency range below 1 kHz.