The Brown Note is an infrasonic frequency rumored to cause humans to lose control of their bowels. Effective frequencies reportedly between 5 and 9 Hz, below the audible range for humans (humans cannot hear below around 20 Hz).
The note was tested on the television show Mythbusters using Meyer Sound subwoofers on par in quantity and quality with those used at major rock concerts. The experimenters on the show tried a series of frequencies between 5 and 10 Hz at 120-160 dBSPL, but they were unsuccessful in producing the rumored effects. They all reported some physical anxiety and shortness of breath, even a small amount of nausea, but this is mostly due to the fact that a sound at that frequency and intensity moves air rapidly in and out of one's lungs.
This experiment was somewhat flawed. The first problem is due to the Mythbusters use of discrete frequencies instead of frequency sweeping. It can be argued that everyone's bowels must have a different resonant frequency. In order to pinpoint an individual rectum's "brown note", one would have to move continuously from 5Hz up to 20Hz until the desired effect was achieved. Also, many rumors state that the "Brown Note" is actually located at 17Hz. Since the Mythbusters did not go over 10Hz, their experiment was incomplete. The brown note remains unconfirmed.
So-called "brown noise" was featured in an episode of South Park (Worldwide Recorder Concert ) as a sound that caused people to lose their bowels uncontrollably, though the sound in the show was a low tone. Real "brown noise" is a well-defined type of noise based on Brownian motion.
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