7 days ago
Owls inspire new revolutionary noise reduction technology
By Stephen Beech
Owls have inspired new noise reduction technology.
The silent flight of the aerial predators is possible because their skin and feathers dampen sound by absorbing high- and low-frequency flight noise.
Inspired by that natural soundproofing, Chinese scientists have developed a two-layer aerogel that mimics the structures inside owl feathers and skin to reduce sound pollution.
They say the new material could be used in cars and manufacturing facilities to reduce traffic and industrial noise.
Previous research has shown that excessive noise can cause hearing loss and can worsen health conditions, including heart disease and type 2 diabetes.
While eliminating the source of noise pollution isn't feasible, soundproofing materials help dampen it.
But traditional materials absorb either high-frequency sounds, such as squealing brakes, or low-frequency sounds, like the deep rumbling of a car engine.
That means engineers often layer multiple types of soundproofing materials to achieve full-spectrum noise control, which adds weight and bulk.
To overcome the issue, researchers at Tiangong University in China turned to owls for inspiration.
Study leader Dr. Dingding Zong said, "The owl uses its soft feathers and porous skin to remain whisper-quiet during flight."
The researchers' goal was to engineer a similarly versatile broadband sound absorber.
The team froze droplets of hexane into a layer of soft material, using a technique called emulsion-templated freeze-reconstruction.
Dr. Zong said removing the frozen hexane revealed a honeycomb-like pattern in the material.
The researchers then added a second layer with silicon nanofibres instead of hexane droplets to create a fibrous pattern.
Dr. Zong said, "The resulting light, porous two-layer aerogel mimics the structures in owl skin and feathers.
"The bottom porous layer resembles the bird's skin with microscopic cavities that cancel out low-frequency noise; and the top feather-inspired layer, made of fluffy nanofibres, dampens high-frequency sounds."
The findings, published in the journal ACS Applied Materials and Interfaces, showed that the owl-inspired aerogels can absorb 58% of sound waves that strike it, surpassing the threshold for effective noise control materials.
The researchers also found that the aerogels reduce 87.5 decibels of automobile engine noise to a safe level of 78.6 decibels, which is a better reduction than existing high-end noise absorbers.
The researchers believe the study paves the way for high-performance, lightweight and durable sound-absorbing materials that can "significantly alleviate" noise pollution from industrial equipment and traffic.
The post Owls inspire new revolutionary noise reduction technology appeared first on Talker.
Copyright Talker News. All Rights Reserved.
