Editing Brown note

{{Short description|Urban myth}}
{{Distinguish|Brownian noise}}

The '''brown note''' (sometimes '''brown tone''' or '''frequency''') is a hypothetical [[Infrasound|infrasonic]] frequency capable of causing [[fecal incontinence]] by creating [[acoustic resonance]] in the human bowel. Considered an [[urban myth]], the name is a [[metonymy|metonym]] for the common color of human [[faeces]]. Attempts to demonstrate the existence of a "brown note" using sound waves transmitted through the air have failed.

Frequencies supposedly involved are between 5 and 9 [[Hertz|Hz]], which are below the lower frequency limit of [[hearing range#Humans|human hearing]]. High-power sound waves below 20 Hz are felt in the body.

==Physiological effects of low frequency vibration==
{{seealso|Infrasound#Human reactions}}

Air is a very inefficient medium for transferring low frequency vibration from a transducer to the human body.<ref>{{Cite journal |url=http://adsabs.harvard.edu/abs/1977JSV....53..605R |title=Tempest, W. ''Infrasound and low frequency vibration'' (1977). Academic Press Inc. (London) Ltd |bibcode=1977JSV....53..605R |access-date=2007-11-10 |archive-date=2008-02-01 |archive-url=https://web.archive.org/web/20080201123920/http://adsabs.harvard.edu/abs/1977JSV....53..605R |url-status=live |last1=Rood |first1=G. |journal=Journal of Sound and Vibration |year=1977 |volume=53 |issue=4 |page=605 |doi=10.1016/0022-460X(77)90533-8 }}</ref> 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&nbsp;dB were achieved at frequencies of 2–3&nbsp;Hz. Test frequencies ranged from 0.5&nbsp;Hz to 40&nbsp;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 legend|urban myth]].<ref>[https://web.archive.org/web/20071231012618/http://srforums.prosoundweb.com/index.php/mv/tree/27986/261708/72/ ProSoundWeb: ''some effects of low end''] (bulletin board entry by [[Tom Danley]])</ref><ref>[https://web.archive.org/web/20080113051923/http://www.danleysoundlabs.com/matterhorn.htm ''The Matterhorn'']</ref>

== Testing by Mythbusters ==
In February 2005 the television show ''[[MythBusters]]'' attempted to verify whether the "brown note" was a reality. 

They used twelve [[Meyer Sound]] 700-HP [[subwoofer]]s—a model and quantity that has been employed for major [[Rock music|rock]] concerts.<ref>{{cite web |url=http://www.discovery.com/tv-shows/mythbusters/mythbusters-database/brown-note/ |title=Brown Note &#124; MythBusters |publisher=Discovery |date=2012-04-11 |access-date=2016-05-29 |archive-date=2016-05-11 |archive-url=https://web.archive.org/web/20160511130630/http://www.discovery.com/tv-shows/mythbusters/mythbusters-database/brown-note/ |url-status=live }}</ref><ref>{{cite web| url=http://www.meyersound.com.au/brownnote.shtm| title=Brown Note| publisher=Meyer Sound| year=2000| access-date=2006-08-30| url-status=dead| archive-url=https://web.archive.org/web/20060906094120/http://www.meyersound.com.au/brownnote.shtm| archive-date=2006-09-06}}</ref> Normal operating frequency range of the selected subwoofer model was 28&nbsp;Hz to 150&nbsp;Hz<ref>{{Cite web |url=http://www.meyersound.com/pdf/products/concert_series/700-hp_ds.pdf# |title=Meyer Sound 700-HP UltraHigh-Power Subwoofer datasheet |access-date=2007-11-14 |archive-url=https://web.archive.org/web/20071021075207/http://www.meyersound.com/pdf/products/concert_series/700-hp_ds.pdf# |archive-date=2007-10-21 |url-status=dead }}</ref> but the 12 enclosures at ''MythBusters'' had been specially modified for deeper bass extension.<ref name=Meyer2004>{{cite web|url=http://meyersound.com/news/2004/brown_note/index.php|title=Meyer Sound Gets Down to Basics in MythBusters Episode|date=September 2004|publisher=Meyer Sound Laboratories|access-date=September 1, 2010|archive-url=https://web.archive.org/web/20110714081338/http://meyersound.com/news/2004/brown_note/index.php#|archive-date=2011-07-14|url-status=dead}}</ref> 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' [[Bass reflex|tuning ports]] were blocked and their input cards were altered. The modified cabinets were positioned in an open ring configuration, in four stacks, with each stack containing three subwoofers. 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 [[Microphone#Measurement microphones|measurement microphone]], displayed and recorded sound pressure levels.<ref name=Meyer2004/> 

The hosts on the show tried a series of frequencies as low as 5&nbsp;Hz, attaining a level of 120&nbsp;[[decibel]]s of [[sound pressure]] at 9&nbsp;Hz and up to 153&nbsp;dB at frequencies above 20&nbsp;Hz, but the rumored physiological effects did not materialize.<ref name=Meyer2004/> 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 [[lung]]s.  The show declared the brown note myth "busted".

==See also==
* [[Acoustic resonance]]
* [[Feraliminal Lycanthropizer]] – A fictional psychotechnographic machine
* [[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
* [[Tesla's oscillator]] – A vibrating machine which is claimed to have the effect of a "mechanical laxative", causing subjects to run straight to the bathroom after use
* "[[World Wide Recorder Concert]]" – A ''South Park'' episode involving a fictional brown note

== References ==
<references/>

{{DEFAULTSORT:Brown Note}}
[[Category:Sound]]
[[Category:Urban legends]]
[[Category:Ultrasound]]
[[Category:Fictional energy weapons]]
[[Category:Defecation]]