

Activists planning protests at the forthcoming Democratic National Convention in Denver are wary of a police weapon they refer to as "Crap Cannon." Luckily for them, it doesn't exist. Fox News filed this report:

Also called “Brown Note,” [the cannon] is believed to be an infrasound frequency that debilitates a person by making them defecate involuntarily. Mark Cohen, co-founder of Re-create 68, an alliance of local activists working for the protection of first amendment rights, said he believes this could be deployed at the convention in August to subdue crowds... Cohen, who described Brown Note as a “sonic weapon used to disrupt people’s equilibrium,” cited eyewitness accounts of its use during free-trade agreement protests in Miami in 2003... His group is preparing against a possible attack by Brown Note and other crowd-control measures by dispatching street medics at the convention trained in treating injuries in demonstration situations.

He should save himself the time. While the story of a frequency that liquefies bowels has been going around for many years, the facts don't really back the tale up. Mythbusters tackled it in 2005, concluding:

Even after testing a wide range of sub-audible and near-sub-audible noises on him, not once did Adam lose control of his bowels. Some discomfort was reported however, due to the effects of low-frequency sound on the lungs.

Fox also turns to Mythbusters – specifically Dr. Roger Schwenke, an acoustician who appeared on the show's "Brown Note" episode – and concludes that "there is no scientific evidence that proves such frequencies cause involuntary defecation."

You might argue that Mythbusters is not right there on the cutting edge. For that, you need look no further than Dr. Jürgen Altmann of the Bochum Verification Project, who carried out the definitive review of all available literature on the effects of acoustic weapons:

Evidence for bowel spasms and uncontrolled defecation is even scarcer. Among all the literature surveyed for this article, the only hint found was one on “digestive troubles” observed during experiments with a strong 16-Hz siren. These were, however, not specified at all, and the explanation immediately following talked of objects vibrating in clothing pockets. In the low frequency exposures up to 150 dB no bowel spasms were observed.

The same holds for low-frequency animal experiments. Here it is noteworthy that also in reviewing vibration experiments no mention was made of bowel spasms or uncontrolled defecation.

Naturally, he gives full references for those wishing to check the facts. (Altmann debunks a lot more myths about the power of acoustic weapons, many of them dating back to the tall tales of Gavreau's legendary sonic weapon. That give us Kate Bush's fab Experiment IV, at least, but not a lot of science.)

So chalk this up as another example of the awesome power of the urban myth. But like all myths, this one does have a teeny-tiny kernel of truth. At 2004's Republican National Convention, authorities deployed a

Long Range Acoustic Device, a super-loudhailer/nonlethal-weapon. But they never used the thing, Dr. Altman notes. "Protesters were at too short distance, so the normal loudspeakers sufficed." If you do get hit with an LRAD blast, it'll make your ears ring, if the machine is turned way up. But no brown stuff will result.

The authorities might try harder to dispel these myths. Equally though, they might find that the effects of crowd control weapons can be greatly enhanced by just this sort of fear.