What is it about?
Sound manipulation (eg. absorption) always require a concrete material or structure (eg. foams) in which physical transformation, such as dissipation, may occur. We show that a layer of ionized air can achieve such manipulation in an ethereal manner thanks to a dedicated active control, and that it even outperforms any existing material (almost 100% sound absorption from at least 20 Hz up to 2 kHz). Experimental assessments confirms the outstanding performance of this new kind of "plasmacoustic metalayer".
Photo by Ahmad Dirini on Unsplash
Why is it important?
Sound waves manipulation covers a wide range of physical phenomena such as absorption, reflection, transmission, diffusion, etc. Usually, these processes rely on a material interface, within which physical transformation of incident sound waves may occur at the mesoscopic scale (in the range of micrometers). For example, sound absorption occurs in porous materials, inside which networks of thin connected pores channel the fluid movements, resulting in friction losses that eventually make the sound energy vanish. Up to now, it was strictly impossible to envision such a mechanism happening without an intermediate material. Here, we demonstrate how a plasma (layer of ionized air) can achieve such acoustic manipulation in a somewhat ethereal manner.
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This page is a summary of: Ultrabroadband sound control with deep-subwavelength plasmacoustic metalayers, Nature Communications, May 2023, Springer Science + Business Media,
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