Moth wings pave the way toward a less-noisy future by inspiring ultra-thin sound absorbers

Amazing stuff! As they say imitation is the sincerest of flattery. This not my first blog about this subject, see here. It appears, we are coming closer to turn the recent discovery of moth acoustic camouflage into practical applications.

"... “What is even more impressive is that the wings are doing this whilst being incredibly thin, with the scale layer being only 1/50th of the thickness of the wavelength of the sound that they are absorbing,” ..."

From the abstract:

"In noise control applications, a perfect metasurface absorber would have the desirable traits of not only mitigating unwanted sound, but also being much thinner than the wavelengths of interest. Such deep-subwavelength performance is difficult to achieve technologically, yet moth wings, as natural metamaterials, offer functionality as efficient sound absorbers through the action of the numerous resonant scales that decorate their wing membrane. Here, we quantify the potential for moth wings to act as a sound-absorbing metasurface coating for acoustically reflective substrates. Moth wings were found to be efficient sound absorbers, reducing reflection from an acoustically hard surface by up to 87% at the lowest frequency tested (20 kHz), despite a thickness to wavelength ratio of up to 1/50. Remarkably, after the removal of the scales from the dorsal surface the wing's orientation on the surface changed its absorptive performance: absorption remains high when the bald wing membrane faces the sound but breaks down almost completely in the reverse orientation. Numerical simulations confirm the strong influence of the air gap below the wing membrane but only when it is adorned with scales. The finding that moth wings act as deep-subwavelength sound-absorbing metasurfaces opens the door to bioinspired, high-performance sound mitigation solutions."

Moth wings pave the way toward a less-noisy future by inspiring ultra-thin sound absorbers Sometimes, copying nature can help us find amazing design ideas.

Moth wings as sound absorber metasurface (open access)

Moth wing-inspired sound absorbing wallpaper in sight after breakthrough Experts at the University of Bristol have discovered that the scales on moth wings act as excellent sound absorbers even when placed on an artificial surface.