Brown note
The brown note, also sometimes called the brown frequency or brown noise, is a hypothetical
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.
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
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
- 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
- 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.