A low-frequency sound absorption structure easily manufactured by machine for transformers noise

Ke Xu; Kanyu Wang; Qinhao Lin; Guoqing Di

doi:10.59400/sv3786

A low-frequency sound absorption structure easily manufactured by machine for transformers noise

Ke Xu
College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
Kanyu Wang
College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
Qinhao Lin
Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou 313001, China
Guoqing Di
College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China

Innovation Center of Yangtze River Delta, Zhejiang University, Jiaxing 314102, China

Article ID: 3786

DOI: https://doi.org/10.59400/sv3786

Keywords: low-frequency, tonal noise, sound absorption materials, acoustic metamaterials, transformer noise

Abstract

Many tonal noises existing in environment have high annoyance degree. It is necessary to develop acoustic materials for targeted absorption of tonal noise in order to reduce its impact. As the primary noise source in substations, transformers emit low-frequency noise with distinct tonal characteristics. According to basic constraints of materials in substations, such as fire resistance, weather resistance, and easy manufacturability by machine, a sound absorption metamaterial (SAM) is developed for absorption of noise from 110 kV transformers in this study. SAM is an aluminum alloy flat plate formed by topological arranging several basic sound absorption units on a plane. Each basic unit consists of two Helmholtz resonators stacked vertically, both of which have an inserted duct. Acoustic performance of SAM is studied by theoretical analysis, numerical simulation, and experimental measurement. Analysis results showed that ratios of its surface acoustic impedance to air acoustic impedance at two resonant frequencies of 100 Hz and 200 Hz were close to 1. Measurement results indicated that sound absorption coefficients respectively reached 0.93 and 0.90 in the normal incident sound field, reached 0.83 and 0.88 in the diffuse sound field. Moreover, the fire resistance grade of SAM reached A1 level, which indicated it was completely non-combustible. Laying SAM on reflective surfaces of structures such as transformer firewalls can reduce the impact of low-frequency noise.

Published

2026-01-06

How to Cite

Xu, K., Wang, K., Lin, Q., & Di, G. (2026). A low-frequency sound absorption structure easily manufactured by machine for transformers noise. Sound & Vibration, 60(1). https://doi.org/10.59400/sv3786

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Vol. 60 No. 1 (2026)

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Article

This work is licensed under a Creative Commons Attribution 4.0 International License.

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