Brown note

For similar phrases, see Brown note (disambiguation).

The brown note is a theoretical infrasonic frequency that would cause humans to lose control of their bowels due to resonance. There is no scientific evidence to support the claim that a "brown note" (transmitted through sound waves in air) exists.

The name is metonymy for the color of human feces. Frequencies supposedly involved are between 5 and 9 Hz, which is below 20 Hz, 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. The only other vibrations titled with colors are the colors of noise and blue notes.

Television show tests

MythBusters used twelve Meyer Sound 700-HP subwoofers—a model and quantity that has been employed for major rock concerts.^[1] Normal operating frequency range of the selected subwoofer model was 28 Hz to 150 Hz^[2] but the 12 enclosures at MythBusters had been specially modified for deeper bass extension.^[3] 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 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.^[3] The experimenters 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.^[3] The test subjects all reported some physical anxiety and shortness of breath, even a small amount of nausea, but this was dismissed by the participants, noting that sound at that frequency and intensity moves air rapidly in and out of one's lungs.

Another show, Brainiac: Science Abuse, claimed to have performed an experiment using 22.275 Hz (according to the show's producers used by Japan's police and tested by the French military). During the programme, they broadcast the note over the air (and into the living rooms of viewers) in an attempt to cause bowel movements among those who had chosen to stay in the room despite repeated warnings and opportunities to leave. However, sound at this frequency at a significant volume cannot be generated by television speakers, nor by most subwoofers, nor by the cassette-tape boombox used to generate the note for the test subject. They also alleged to have confirmed the myth with a subject, but this subject was out of camera shot for all of the piece except at the very beginning.

Physiological effects of low frequency vibration

Jürgen Altmann of the Dortmund University of Technology, an expert on sonic weapons, says that there is no reliable evidence for nausea and vomiting caused by infrasound.^[4]

Loud concert levels of subwoofer arrays have been cited as causing lung collapse in individuals who are very close to the subwoofer, especially for smokers who are particularly tall and thin.^[5]

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.^[6]

Air is a very inefficient medium for transferring low frequency vibration from a transducer to the human body.^[7] 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.^[8]

See also

• Acoustic resonance
• Brown noise
• "World Wide Recorder Concert", a South Park episode

References

1. ^ "Brown Note". Meyer Sound. 2000. http://www.meyersound.com.au/brownnote.shtm. Retrieved 2006-08-30. 
2. ^ Meyer Sound 700-HP UltraHigh-Power Subwoofer datasheet
3. ^ ^{a b c} "Meyer Sound Gets Down to Basics in MythBusters Episode". Meyer Sound Laboratories. September 2004. http://meyersound.com/news/2004/brown_note/index.php. Retrieved September 1, 2010. 
4. ^ The Pentagon considers ear-blasting anti-hijack gun — New Scientist
5. ^ Wired. Music Fans, Beware the Big Bass
6. ^ Loud bass music ‘killed student’ Tom Reid, Metro, retrieved 18 June 2010
7. ^ Tempest, W. Infrasound and low frequency vibration (1977). Academic Press Inc. (London) Ltd
8. ^ ProSoundWeb: some effects of low end (bulletin board entry by Tom Danley)