The brown note is a hypothetical infrasonic frequency that would cause humans to lose control of their bowels due to resonance. Attempts to demonstrate the existence of a "brown note" using sound waves transmitted through air have failed.
The name is a metonym for the common color of human feces. Frequencies supposedly involved are between 5 and 9 Hz, which is below the lower frequency limit of human hearing. High power sound waves below 20 Hz are felt in the body, not heard by the ear as sound.
Physiological effects of low frequency vibration
High volume levels at concerts from subwoofer arrays have been cited as causing lung collapse in individuals who are very close to the subwoofers, especially for smokers who are particularly tall and thin.
In September 2009, London student Tom Reid died of sudden arrhythmic death syndrome (SADS) after complaining that "loud bass notes" were "getting to his heart". The inquest recorded a verdict of natural causes, although some experts commented that the bass could have acted as a trigger.
Air is a very inefficient medium for transferring low frequency vibration from a transducer to the human body. Mechanical connection of the vibration source to the human body, however, provides a potentially dangerous combination. The U.S. space program, worried about the harmful effects of rocket flight on astronauts, ordered vibration tests that used cockpit seats mounted on vibration tables to transfer "brown note" and other frequencies directly to the human subjects. Very high power levels of 160 dB were achieved at frequencies of 2–3 Hz. Test frequencies ranged from 0.5 Hz to 40 Hz. Test subjects suffered motor ataxia, nausea, visual disturbance, degraded task performance and difficulties in communication. These tests are assumed by researchers to be the nucleus of the current urban myth.
The report "A Review of Published Research on Low Frequency Noise and its Effects" contains a long list of research about exposure to high-level infrasound among humans and animals. For instance, in 1972, Borredon exposed 42 young men to tones at 7.5 Hz at 130 dB for 50 minutes. This exposure caused no adverse effects other than reported drowsiness and a slight blood pressure increase. In 1975, Slarve and Johnson exposed four male subjects to infrasound at frequencies from 1 to 20 Hz, for eight minutes at a time, at levels up to 144 dB SPL. There was no evidence of any detrimental effect other than middle ear discomfort. Tests of high-intensity infrasound on animals resulted in measurable changes, such as cell changes and ruptured blood vessel walls.
In February 2005 the television show MythBusters used twelve Meyer Sound 700-HP subwoofers—a model and quantity that has been employed for major rock concerts. Normal operating frequency range of the selected subwoofer model was 28 Hz to 150 Hz but the 12 enclosures at MythBusters had been specially modified for deeper bass extension. Roger Schwenke and John Meyer directed the Meyer Sound team in devising a special test rig that would produce very high sound levels at infrasonic frequencies. The subwoofers' tuning ports were blocked and their input cards were altered. The modified cabinets were positioned in an open ring configuration: four stacks of three subwoofers each. Test signals were generated by a SIM 3 audio analyzer, with its software modified to produce infrasonic tones. A Brüel & Kjær sound level analyzer, fed with an attenuated signal from a model 4189 measurement microphone, displayed and recorded sound pressure levels. The hosts on the show tried a series of frequencies as low as 5 Hz, attaining a level of 120 decibels of sound pressure at 9 Hz and up to 153 dB at frequencies above 20 Hz, but the rumored physiological effects did not materialize. The test subjects all reported some physical anxiety and shortness of breath, even a small amount of nausea, but this was dismissed by the hosts, noting that sound at that frequency and intensity moves air rapidly in and out of one's lungs. The show declared the brown note myth "busted."
In the season 3 episode "World Wide Recorder Concert" (episode 17) of the animated show South Park in 2000, the brown note myth is featured prominently; the boys rewrite the music for a worldwide recorder concert to include the brown note (for kids from New York who kept insulting them), with the unintended result that everyone in the world defecates almost simultaneously.
In the season 4 episode "The Curse of Shiva" (episode 13) of The League, Taco (Jon Lajoie) has found a use for the thousands of discarded vuvuzela instruments left over from the 2010 FIFA World Cup hosted by South Africa. The instruments were tinkered with to produce the brown note with hopes that it could then be sold to the military as a weapon.
In the season 1 episode "Angel Boy" (episode 4) of the Adult Swim show Tim and Eric's Bedtime Stories, the character Scotty sings a note that causes attendees at a birthday party to have intense gastrointestinal distress and defecate uncontrollably.
- Acoustic resonance
- Feraliminal Lycanthropizer
- The Mosquito, a commercial device that deters loitering by emitting sound with a very high frequency
- The Republic XF-84H, an experimental aircraft that produced enough noise to cause headaches, nausea and seizures among its ground crew
- The Pentagon considers ear-blasting anti-hijack gun — New Scientist
- Wired. Music Fans, Beware the Big Bass
- Loud bass music ‘killed student’ Tom Reid, Metro, retrieved 18 June 2010
- Tempest, W. Infrasound and low frequency vibration (1977). Academic Press Inc. (London) Ltd
- ProSoundWeb: some effects of low end (bulletin board entry by Tom Danley)
- The Matterhorn
- "Brown Note | MythBusters". Discovery. 2012-04-11. Retrieved 2016-05-29.
- "Brown Note". Meyer Sound. 2000. Archived from the original on 2006-09-06. Retrieved 2006-08-30.
- "Meyer Sound 700-HP UltraHigh-Power Subwoofer datasheet" (PDF). Archived from the original (PDF) on 2007-10-21. Retrieved 2007-11-14.
- "Meyer Sound Gets Down to Basics in MythBusters Episode". Meyer Sound Laboratories. September 2004. Archived from the original on 2011-07-14. Retrieved September 1, 2010.
- Kelly, Kevin. "Set Your Bowel Disruptor To Explosive Diarrhea". io9. Retrieved 2017-10-03.
- AVClub: The League: A Krampus Carol / The Curse of Shiva (by Margaret Eby)
- "Angel Boy - Tim & Eric's Bedtime Stories on Adult Swim Video". Adultswim.com. 2014-08-26. Retrieved 2016-05-29.