Previous shows involving Meyer Sound have explored myths such as the assertion that a duck's quack does not echo (debunked) and whether a human voice can shatter glass (confirmed). When the programme makers set out to apply their zany method to one more myth requiring sound expertise, they again turned to Meyer. "This story started with the myth that deceased Californian naturalist and vaudeville performer Charles Kellogg could extinguish fires using only his voice, and expanded into an investigation into the viability of fighting fires with sound," explains Alice Dallow, producer for the show.
Sound waves were used recently as part of the Prometheus Project, where a group of graduate students at the University of West Georgia manipulated a candle-sized flame in a low gravity environment. The technology obviously has practical use in applications related to the space programme (where traditional fire extinguisher foams will not work due to the lack of gravity), but also in commercial applications where extinguisher chemicals may cause equipment damage. So the question facing the researchers was twofold: would the same experiment work in normal gravity, given the differing behaviour of a flame under those conditions; and, if it did work, could sound waves extinguish anything larger than a candle?
For the first stage of the test, Meyer Sound staff scientist Roger Schwenke and other technicians from the company used a UPJ-1P Compact VariO loudspeaker and an M1D-Sub ultracompact subwoofer. Testing with a larger flame required the added punch of four M3D-Sub directional subwoofers. Frequencies considered optimal for extinguishing fire were pinpointed with the help of a SIM 3 audio analyser. "We had a lot of fun with this one," says Schwenke, "using the loudspeakers and subs to bombard the flame with appropriate frequencies, making it 'dance', and figuring out just what frequencies would manipulate it."
"It takes methodical measurement and analysis to truly understand the behaviour and effects of sound, and we have a good time bringing those things to the Mythbusters' exploits," says company president/CEO, John Meyer. "We've done some amusing experiments with them, but the practical uses and implications of this experiment made it particularly interesting."
(Jim Evans)
