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Moth wing–inspired sound absorbing wallpaper in sight after breakthrough

Mothwing-inspired sound-absorbing wallpaper in sight after breakthrough

Antheraea pernyi. Credit: University of Bristol

Experts from the University of Bristol have found that the scales on the wings of moths have excellent sound-absorbing properties, even when placed on an artificial surface.

The researchers, who recently found that moth wings provide acoustic protection against echolocation calls from bats, investigated whether their structure could contribute to better-performing sound-absorbing panels when not moving in free space.

Bats and moths have been involved in an acoustic arms race between predator and prey since bats evolved echolocation some 65 million years ago. Moths are under tremendous predation pressure from bats and have evolved a plethora of defenses in their pursuit of survival, but it’s the scales on a moth’s wing that hold the key to transforming noise-cancelling technology.

Prof. dr. Marc Holderied, from Bristol’s School of Biological Sciences, said: “What we needed to know first was how well these moth scales would perform when placed in front of an acoustically highly reflective surface, such as a wall.

“We also had to figure out how the absorption mechanisms might change when the shells interacted with this surface.”

Prof. dr. Holderied and his team tested this by placing small sections of moth wings on an aluminum disc and then systematically tested how the orientation of the wing relative to the incoming sound and the removal of scale layers affected absorption.

Mothwing-inspired sound-absorbing wallpaper in sight after breakthrough

Close up of a wing scale. Credit: University of Bristol

Remarkably, they found that moth wings proved to be excellent sound absorbers even when perched atop acoustically solid ground, with the wings absorbing as much as 87% of the incoming sound energy. The effect is also broadband and omnidirectional, covering a wide range of frequencies and sound angles.

“What’s more impressive is that the wings do this while being incredibly thin, with the shell layer being only 1/50th the thickness of the wavelength of the sound they absorb,” explains lead author Dr. Thomas Neil out. “This extraordinary performance qualifies the moth wing as a naturally occurring acoustically absorbent meta-surface, a material with unique properties and capabilities not possible with conventional materials.”

The potential of making ultra-thin sound-absorbing panels has huge implications for the acoustics of buildings. As cities get louder, the need for efficient, non-intrusive noise mitigation solutions grows. Likewise, these lightweight sound-absorbing panels could have a huge impact on the travel industry, with any weight savings in planes, cars and trains increasing efficiency in these modes of transport and reducing fuel consumption and CO2.2 emissions.

Mothwing-inspired sound-absorbing wallpaper in sight after breakthrough

Scale close up. Credit: University of Bristol

Their study is published in Proceedings of the Royal Society A: Mathematical and Physical Sciences† Now the scientists plan to replicate its sound-absorbing performance by designing and building prototypes based on the moth’s sound-absorbing mechanisms. The absorption they have characterized in moth wing scales is all in the ultrasonic frequency range, above what humans can hear. Their next challenge is to design a structure that operates at lower frequencies, while maintaining the same ultra-thin architecture used by the moth.

Prof. dr. Holderied concluded: “Moths will inspire the next generation of sound-absorbing materials. New research has shown that one day it will be possible to decorate the walls of your home with ultra-thin sound-absorbing wallpaper, using a design that replicates the mechanisms that give moths stealth acoustic camouflage.”

Moths and bats have been in an evolutionary struggle for millions of years and we are still discovering their tricks

More information:
Moth wings as a sound-absorbing meta-surface, Proceedings of the Royal Society A: Mathematical and Physical Sciences (2022). DOI: 10.1098/rspa.2022.0046royalsocietypublishing.org/doi … .1098/rspa.2022.0046

Provided by the University of Bristol

Quote: Butterfly wings-inspired sound-absorbing wallpaper in sight after breakthrough (2022, June 14) retrieved June 14, 2022 from https://phys.org/news/2022-06-moth-winginspired-absorberende-wallpaper-sight.html

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