How moths inspired new soundproofing metamaterials

Marc Holderied, Professor of Sensory Biology at University of Bristol, has been fascinated by the acoustic arms race of bats and their moth prey throughout his academic career.

Bats use echolocation and the echo of sound waves from their prey to detect a meal. This drives moths to evolve mechanisms of avoiding predation. Some moths can hear bat calls, changing their flight direction to escape, but not all prey have this ability and have evolved other means.

As part of a BBSRC-funded project, researchers examined scales on the bodies of moths that cannot detect bat calls. They identified unique structures that absorb ultrasound waves, allowing the moths to become ‘invisible’ to echolocating bat predators.

The scale structures on these moths dampen sound ten times more effectively than any man-made sound absorber and have evolved to be thin enough to cover wings. Professor Holderied saw the potential to apply this knowledge to the production of thin and effective sound absorbers for noises experienced by humans.

Professor Holderied received UKRI funding through BBSRC, EPSRC, and £1.3 million from the Strategic Priorities Fund (SPF) Physics of Life programme. The Physics of Life Biological Metamaterials for Enhanced Noise Control Technology project, led by Professor Holderied and Professor Richard Craster at Imperial College London, developed a sound absorber prototype. Further optimisation is being facilitated by a BBSRC grant with the aim of producing products, such as sound-absorbing wallpaper.