The majority of facilities, from apartments to airplanes, are now built with sound-absorbing materials to lessen the droning, echoing, and muttering noises of daily living.
However, the majority of acoustic materials that may muffle sound from people talking, traffic, and music are constructed of plastic foams that are difficult to recycle or decompose.
Researchers have now developed a biodegradable film made from seaweed that efficiently muffles noises in this frequency range.
Seaweed as a soundproof material
Controlling and optimizing the way sound moves throughout a room is key to creating functional spaces.
Foam acoustic panels are a common solution, and they come in a variety of materials and thicknesses tailored to specific sound requirements, as per ScienceDaily.
Most of these forms, however, are made from polyurethane and other polymers that are derived from crude oil or shale gas.
To avoid petrochemicals, researchers have explored more renewably sourced and biodegradable sound-absorbing alternatives.
But many current options are made from plant fibers that don't effectively dampen noises in the most useful range of sound frequencies, or they are too thick or unwieldy to fabricate.
So, Chindam Chandraprakash and colleagues wanted to develop a plant-derived, biodegradable material that would be simple to manufacture and that could absorb a range of sounds.
Along with other plant-derived additives, the researchers made thin films of agar, a jelly-like substance derived from seaweed, and adjusted the films' thickness and porosity.
The researchers tested how well the films muffled sound across a variety of frequencies, from a low hum to a harsh shriek, after putting the materials through a battery of tests.
The team built a sound tube with a speaker at one end and a test film put at the other end to achieve this.
The quantity of sound released by the speaker and the amount of sound reflected off the film were measured by microphones in the tube's midsection.
These tests revealed that the most agar-porous films had the best sound-absorbing properties and behaved comparably to conventional acoustic foams.
The researchers will investigate different biologically derived film materials and ways to alter the agar films to offer them additional desirable features, such as flame resistance.
Read more: Bat's Vision and Echolocation Empower Them to Be Top Nocturnal Predators
Using moth wings in soundproofing
Moth wings are great sound absorbers, according to research from the University of Bristol in England.
This finding might have a significant influence on soundproofing techniques for buildings and vehicles, as per CBC.
Because many moths have patterns on their wings that match the color of tree bark, it might be challenging for predators to identify them, making moths masters of camouflage.
Now, researchers have discovered that another method they conceal themselves is by using their wings to absorb the noises made by bats, one of their major predators, which may provide information about how to lessen sound that reflects off of solid objects.
Since significantly less sound is reflected when the bat uses echolocation to detect prey, the moth is essentially invisible to the bat thanks to its sound-absorbing wings.
Similar to the radar-absorbing coatings used on stealth aircraft, this effect.
Ultrasonic sound waves, which bats generate at a higher frequency than humans can hear, are absorbed by the microscopic scales that make up a moth's wing.
In an experiment, a little piece of a wing was put over an aluminum disc that was extremely reflective, and sound waves were then directed at the disc to measure the amount of sound that was reflected back.
To their surprise, the researchers discovered that the moth wing absorbed up to 87% of the sound waves that hit the surface over a wide variety of frequencies and angles.
Astonishingly, the wing scales are far thinner than typical soundproofing material, measuring only 2% as wide as the wavelength of sound that they are absorbing.
According to their predictions, buildings, homes, and transportation, especially aircraft which must be soundproofed against propeller and jet noise could be greatly impacted if the microscopic structure of a moth wing could be replicated in manufacturing, scaled up to industrial size, and tuned to the lower sound frequencies we hear in daily life.
Ultra-thin sound absorbers would reduce the weight of airplanes, which would reduce fuel consumption.
The wings' leading-edge serrations aid in minimizing turbulence and smoothing out airflow, which helps to reduce noise.
The wings' velvety down feather texture and soft fringe around the feather's trailing edge further reduce noise.
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