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
Sound travels in waves, which are simply variations of pressure in a medium—whether 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. 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.
"We don't know exactly what's going on," Plaks says, now a student at the Georgia Institute of Technology.
