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Wednesday 19 March 2014

7 AMAZING THINGS YOU CAN DO WITH SOUND


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7 Amazing Things You Can Do With Sound Waves
By Laura Kiniry,
Popular Mechanics, 17 March 2014.

Sound can identify the contents of homemade bombs, measure the temperature in a nuclear reactor, and even perform brain surgery.

1. Levitate an Object


Scientists have known since the 1970s how to levitate objects with sound waves. Japanese researchers at the University of Tokyo have recently expanded this idea by not only moving (in this case) tiny particles but also having them move in 3D.

Acoustic levitation employs the nonlinear effects of intense sound waves - some audible, some not - and uses the difference in pressure between these waves and an object to raise the object and keep it suspended in mid-air. The Japanese researchers have added a third element: four panels of speakers that face each other and emit inaudible high frequencies. Together they create a controlled point where all the frequencies intersect. Then, when scientists adjust the frequency emitted from each panel, they can move the point - and the particles - around.

2. Make Breathing Easier

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Acoustics engineer Sandy Hawkins created the Lung Flute in 2009 as a way to use low-frequency sound waves to help people with emphysema and other respiratory illnesses. The handheld device consists of a long plastic tube with an attached mouthpiece and a Mylar reed inside. A patient blows into the mouthpiece between 15 and 20 times, sending a steady vibration into the chest that mimics the frequency of cilia - the hair-like organelles that help dislodge dirt and mucus in the lungs. In doing so, the Lung Flute stimulates the lungs' natural secretion system and works in unison with it for easier breathing.

3. Conduct Brain Surgery

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Created by private healthcare company InSightec, ExAblate is a medical device that uses magnetic resonance imaging (MRI) combined with guided, focused ultrasound to conduct non-invasive brain surgery. Doctors use the MRI to locate a tumour. They then use the helmet-like ExAblate to produce high-frequency sound waves that pass through the skull. The waves produce heat-creating friction that slowly destroys the tumour.

To avoid any acoustic distortion from the skull, the device is equipped with more than 1000 ultrasound transducers, the devices that send and receive sound waves, each of which can focus individually. During the procedure, chilled water also circulates around the skull to prevent overheating.

4. Create Electricity


To bring much-needed energy to developing countries, a team led by researchers at the U.K.'s University of Nottingham created the SCORE Stove, a wood-burning stove that converts heat into sound and then sound into electricity. The stove features a pipe that harnesses excess heat from cooking. Once contained, the heat travels into the SCORE Stove's thermo-acoustic engine, warming the compressed air that's inside and causing it to vibrate, producing intense sound waves. A linear alternator then converts these sound waves into electricity. The stove has no moving parts, so it's easy to fix. It also can produce enough power after 3 hours of use to light a home for a night.

5. Take Temperatures

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Not all thermometers are created equal. Because extremely high temperatures in places such as nuclear reactors can cause drift, which leads to inaccuracy, scientists at the U.K.'s National Physical Laboratory are turning to acoustic thermometers in lieu of traditional ones. The acoustic thermometer is a gas-filled ceramic tube with a speaker on one end and a microphone on the other. Sound waves travel from the former to the latter, measuring the time it takes to get there. The warmer the air, the faster sound travels, and scientists can use that information to determine the temperature of the gas.

6. Clear Windshields (Without Wipers)

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British car manufacturer McLaren is planning to utilize the same technology used in fighter jets to keep windshields clean, employing sound waves to create a water-deflecting field. While the exact technology is under wraps, we know it forgoes both a protective coating and a windshield wiper for the type of ultrasonic generator that can be attached unobtrusively in a corner. Its constant high-frequency vibration keeps both H20 and dirt from sticking to the glass.

7. Detect Bombs


Vanderbilt engineering professor Douglas Adams wants to use sound waves to detect and identify homemade bombs from a distance. He's developing a remote acoustic detection system that will be able to tell the difference between low-yield and high-yield explosives via their vibrations. Adams and his team will aim both a sonic beam and a laser vibrometer - which is essentially an instrument that can measure pulsations from a distance - onto the homemade bomb and record how it vibrates. The less dense the container, the greater the vibrations. The system is being developed as part of a major Office of Naval Research grant.

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[Source: Popular Mechanics. Edited. Some links added.]


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