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Brown note

The brown note, also sometimes called the brown frequency or brown noise, is a hypothetical infrasonic frequency capable of causing fecal incontinence by creating acoustic resonance in the human bowel. The name is a 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 Hz, which are 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

Air is a very inefficient medium for transferring low frequency vibration from a transducer to the human body.[1] 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.[2][3]

MythBusters testing

In February 2005 the television show MythBusters attempted to verify whether the "brown note" was a reality.

They used twelve Meyer Sound 700-HP subwoofers—a model and quantity that has been employed for major rock concerts.[4][5] Normal operating frequency range of the selected subwoofer model was 28 Hz to 150 Hz[6] but the 12 enclosures at MythBusters had been specially modified for deeper bass extension.[7] 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, 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 measurement microphone, displayed and recorded sound pressure levels.[7]

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.[7] 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".

See also

References

  1. ^ Rood, G. (1977). "Tempest, W. Infrasound and low frequency vibration (1977). Academic Press Inc. (London) Ltd". Journal of Sound Vibration. 53 (4): 605. Bibcode:1977JSV....53..605R. doi:10.1016/0022-460X(77)90533-8. from the original on 2008-02-01. Retrieved 2007-11-10.
  2. ^ (bulletin board entry by Tom Danley)
  3. ^
  4. ^ "Brown Note | MythBusters". Discovery. 2012-04-11. from the original on 2016-05-11. Retrieved 2016-05-29.
  5. ^ . Meyer Sound. 2000. Archived from the original on 2006-09-06. Retrieved 2006-08-30.
  6. ^ (PDF). Archived from the original (PDF) on 2007-10-21. Retrieved 2007-11-14.
  7. ^ a b c . Meyer Sound Laboratories. September 2004. Archived from the original on 2011-07-14. Retrieved September 1, 2010.

brown, note, confused, with, brownian, noise, brown, note, also, sometimes, called, brown, frequency, brown, noise, hypothetical, infrasonic, frequency, capable, causing, fecal, incontinence, creating, acoustic, resonance, human, bowel, name, metonym, common, . Not to be confused with Brownian noise The brown note also sometimes called the brown frequency or brown noise is a hypothetical infrasonic frequency capable of causing fecal incontinence by creating acoustic resonance in the human bowel The name is a 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 Hz which are 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 Contents 1 Physiological effects of low frequency vibration 2 MythBusters testing 3 See also 4 ReferencesPhysiological effects of low frequency vibration EditSee also Infrasound Human reactions Air is a very inefficient medium for transferring low frequency vibration from a transducer to the human body 1 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 2 3 MythBusters testing EditIn February 2005 the television show MythBusters attempted to verify whether the brown note was a reality They used twelve Meyer Sound 700 HP subwoofers a model and quantity that has been employed for major rock concerts 4 5 Normal operating frequency range of the selected subwoofer model was 28 Hz to 150 Hz 6 but the 12 enclosures at MythBusters had been specially modified for deeper bass extension 7 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 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 Bruel amp Kjaer sound level analyzer fed with an attenuated signal from a model 4189 measurement microphone displayed and recorded sound pressure levels 7 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 7 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 See also EditAcoustic 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 Worldwide Recorder Concert a South Park episode involving a fictional Brown NoteReferences Edit Rood G 1977 Tempest W Infrasound and low frequency vibration 1977 Academic Press Inc London Ltd Journal of Sound Vibration 53 4 605 Bibcode 1977JSV 53 605R doi 10 1016 0022 460X 77 90533 8 Archived from the original on 2008 02 01 Retrieved 2007 11 10 ProSoundWeb some effects of low end bulletin board entry by Tom Danley The Matterhorn Brown Note MythBusters Discovery 2012 04 11 Archived from the original on 2016 05 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 a b c 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 Retrieved from https en wikipedia org w index php title Brown note amp oldid 1130529128, wikipedia, wiki, book, books, library,

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