A team of researchers from Far Eastern Federal University (FEFU), research centers of Russia and the Republic of Korea developed sound absorbing nanofoam, which is effective and cheap in manufacturing. The material can reduce the noise level by 100% more than the standard analogues in response to sound waves of both high and low frequencies, particularly hazardous to human health.
Experts note that reducing the level of noise transmission by 20-22 dB can be considered drastic, and the resulting material is real breakthrough.
According to Alexey Zavyalov, Research Associate, FEFU School of Natural Sciences (SNS), noise is a problem of modern industrial civilization. For example, the noise level monitoring in South Korean cities is conducted 24/7; for the East Asian countries such control is relevant to high-speed rail lines, and in our country the issue is especially acute in big cities and in the automotive industry.
“At the moment, various porous materials are used for soundproofing,” said Alexey Zavyalov. “But their noise-absorbing properties can be considerably enhanced with the help of nanoporous granules, which are introduced into the material structure and form internal channels in it. The improved acoustic characteristics of the newest hybrid nanofoam were obtained by additional enrichment of the usual sound-absorbing foam with porous granules of silica and magnetite nanoparticles. The new material is structurally similar to airgel, but it is devoid of its shortcomings—high prices and engineering problems.”
The developer also noted that nanofoam is unique in that it can significantly reduce low-frequency noise. Infra- and low-frequency vibrations and noise (less than 0.4 kHz) are most harmful and dangerous for human health and life: their long-term effects lead to serious diseases and pathologies.
“Due to such approach, we achieved noise absorption efficiency in the range of 2.0–6.3 kHz and at lower frequencies 0.5–1.6 kHz. The degree of absorption was increased by 60–100%, and the sound transmission was reduced by 20–22 dB, regardless of the type of nanofiller,” the scientist added.
Researchers of the FEFU SNS Academic Department of Nuclear Technology, institutes of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk State Technical University, and University of Ulsan (South Korea) took part in the development of the unique material. The study is supported by the grant of the Russian Science Foundation and its findings have been published in the Applied Acoustics Journal.