Apparently, sound can put out flames but nobody really knows why
When Fire Strikes, Stop, Drop and... Sing?
For over 150 years, scientists have known that fires can be extinguished with sound waves, but they still don't know how
By Alison Snyder
FIRE SILENCE: Sound can extinguish flame as this video proves, but scientists still are not sure how.
"I throw more power into my voice, and now the flame is extinguished," wrote Irish scientist John Tyndall about his experiments with sound and fire in 1857. Countless public demonstrations and a handful of lab tests later, researchers are still struggling to determine exactly how sound snuffs flames.
Sound travels in waves, which are simply variations of pressure in a mediumówhether solid, liquid or gas. The energy from vibrating objects, such as speaker membranes, moves from particle to particle in the air in a repeating pattern of high- and low-pressure zones that we perceive as sound. According to the ideal gas law, temperature, pressure and volume are related; therefore, a decrease in pressure can lead to a corresponding decrease in temperature, which may explain how sound can extinguish a flame.
In 2004 Dmitriy Plaks and several of his fellow students at the University of West Georgia tested whether sound waves can douse fires in hopes of using sound to extinguish flames in a spacecraft. VIDEO They placed a candle in a large topless chamber with three bass speakers attached to the walls. The candle was lit and the Canadian rock band Nickelback's "How you remind me" was pumped through the subwoofers. Within roughly 10 seconds, once the song hit a low note, the flame was out, according to results published in 2005 in The Journal of the Acoustical Society of America.
There is interest in using this method to put out flames in spaceships (Source
). Everybody keeps saying that nobody knows how it works but I am puzzled why. Acoustic effects are well understood, as is combustion. Sound waves cause compression and rarefaction of air. Combustion (fire) involves certain rates of interaction between cumbustible materials and air. So, somehow, it must interfere with the interaction between them. Sound can create standing waves of compression and rarefaction. These must be factors in the mechanism of acoustic fire suppression.