Moth wings and sound absorbtion

First it was owls. Now it’s moths. It seems that, when we want to find ways to make the human world quieter, we only need look to animals. Aeroplane and engine designers put serrated edges on the back of engines and wings to make jets quieter. This emulates the serrated shape of the feathers in owls’ wings which smooth air flow, reducing turbulence and sound.

Now scientists at Bristol University have found that moth wings have incredible sound-absorbing qualities, which could lead to a step change in human technologies for soundproofing buildings and transportation.
The scientists have discovered that moths’ wings absorb the sounds emitted by bats, one of their main predators, making them almost invisible and less likely to end up as dinner. When looked at under a microscope, a moth’s wing is made up of tiny scales with holes that absorb the ultrasonic sound waves that bats make. In fact, researchers found the wing absorbed up to 87% of the sound that struck the surface. Remarkably, the wing scales are only 2% as wide as the width of the wavelength of sound they’re absorbing.

Presupposing the structure of a moth wing could be copied and scaled up to industrial size, this finding could have a huge impact on the way we build our homes, towns, cities and transportation. The significance for the aerospace sector is particularly exciting: ultra-thin sound absorbers would save weight on aircraft and, therefore, save on fuel.