The Hum is a phenomenon, or collection of phenomena, involving widespread reports of a persistent and invasive low-frequency humming, rumbling, or droning noise not audible to all people. Hums have been widely reported by national media in the UK and the United States. The Hum is sometimes prefixed with the name of a locality where the problem has been particularly publicized: e.g., the "Bristol Hum", the "Taos Hum", or the "Bondi Hum".
Data from a Taos Hum study suggests that a minimum of two percent and perhaps as many as 11 percent of the population could detect the Taos Hum, and the Daily Telegraph in 1996 likewise reported a figure of two percent of people hearing the Bristol Hum.:575 For those who can hear the Hum it can be a very disturbing phenomenon and it has been linked to at least three suicides in the UK. However, amongst those who cannot hear the hum and some specialists, there has been skepticism about whether it, in fact, exists.
- 1 Description
- 2 History
- 2.1 London and Southampton, UK (1940s)
- 2.2 Bristol, England, UK (1979)
- 2.3 Largs, Scotland, UK (1980s)
- 2.4 Taos, New Mexico, US (1992)
- 2.5 Kokomo, Indiana, US (1999)
- 2.6 Auckland, New Zealand (2006)
- 2.7 Calgary, Alberta, Canada (2008)
- 2.8 Cambridge, England, UK (2009)
- 2.9 Windsor, Ontario, Canada (2009)
- 2.10 Woodland, England, UK (2011)
- 2.11 Beaufort, County Kerry, Ireland (2012)
- 2.12 Seattle, Washington, US (2012)
- 2.13 Wellington, New Zealand (2012)
- 3 Possible explanations
- 4 Media coverage
- 5 In popular culture
- 6 See also
- 7 References
- 8 Further reading
- 9 External links
The essential element that defines the Hum is what is perceived as a persistent low-frequency sound, often described as being comparable to that of a distant diesel engine idling, or to some similar low-pitched sound for which obvious sources (e.g., household appliances, traffic noise, etc.) have been ruled out. There are a number of audio reproductions of the Hum available on the web.
In his early days, the hearer typically feels frustrated and annoyed because his personal privacy is being disturbed by a force, the ever-present Hum, for which he cannot physically locate the source. His attempts to share his disturbance with his loved ones are met with skepticism; their dismissal of his complaint causes him further frustration and self-doubt. His quality of life has been affected. Once he seeks professional attention from otologists, he still rarely obtains any helpful advice, because most commonly, his hearing will be found to reflect normal to above-average hearing ability. The diagnosis of tinnitus is then vehemently rejected by those hearers who already experience tinnitus because they recognize the different qualities of the two phenomena. The hearer continues his search for the source of the Hum, first inspecting the facilities within his dwelling and then extending his search further into the neighborhood. An understandable result of the hearer’s desperate and fruitless search is paranoia, feeling victimized by a disturbance he knows is real – but one he cannot share with others. It is therefore easy to see how this sufferer might be drawn to outlandish explanations for his very real ailment. After several years, some hearers report that the Hum becomes less important; it is no longer annoying, or it disappears completely. :575–576
Hum can form beats with external sounds. In a questionnaire 60% of hearers report to perceive such a sound-interactive Hum that may form beats with, lock into and match the frequency of an external sound. A time lag of 2 - 3 days until Hum reappears after longer air travels has been reported by 55 % of hearers, and 37 % of them report that they can stop their Hum during purposeful head movements. 
Other elements seem to be significantly associated with the Hum, being reported by an important proportion of hearers, but not by all of them. Some people hear the Hum only, or much more, inside buildings as compared with outdoors. Some perceive vibrations that can be felt through the body. Earplugs are reported as not decreasing the Hum.
Only a handful of articles have been published in the scientific literature including Deming, 2004; Broner, 1978; Cowan, 2003; Fox, 1989; Leventhall, 2003; Mullins & Kelly, 1995, 1998; Hanlon, 1973; Vasudevan & Gordon, 1977; Wilson, 1979; Frosch, 2013. 
The World Hum Database and Mapping Project was launched in December 2012 by Dr. Glen MacPherson, in order to build detailed mappings of hum locations and to provide a database of Hum-related data for professional and independent researchers.
London and Southampton, UK (1940s)
More than 2,000 people reported hearing sounds dating back to the 1940s in the London and Southampton areas of Great Britain. Deming cited Glasgow, Scotland's Sunday Herald 1995 report claiming that the Hum was, "first reported in the late 1950s when people in Britain began to report hearing a most unusual noise—a combination of a humming, droning, and buzzing sound.":573
Bristol, England, UK (1979)
In Britain, the most famous example was the Bristol Hum that made headlines in the late 1970s.
Largs, Scotland, UK (1980s)
Since the 1980s, the Hum has been bothering people living in coastal towns in the west coastal area of Scotland including Largs, a coastal town about 31 km west of Glasgow.:574
Taos, New Mexico, US (1992)
By order of the government, Mullins and Kelly of the University of New Mexico extensively investigated the source of the Taos Hum. In one of their studies, hearers were asked to match their Hum with a sound generator. Hearers matched at the same time and place reproducibly perceived Hum. However, hearers did not match the frequency of the supposed external Taos Hum. Instead, hearers matched to different frequencies ranging from 32.3 Hz to 80.5 Hz with modulation frequencies from 0 to 2.3 Hz. Additionally, taking into account the very low background noise measured at this area, it became quite clear to Mullins and Kelly that the source of the Taos Hum did not appear to be noise in the environment.
Kokomo, Indiana, US (1999)
Kokomo, a city of 47,000, allocated $100,000 in 2002 to investigate a hum after nearly 100 complaints were made since 1999. Some sufferers blamed physical symptoms on the hum, including headaches, nausea, diarrhea, fatigue, and joint pain, with one reporting that her health improved when she moved out of the town. In November 2002, acoustic consultants Acentech was hired by the Board of Public Works and Safety of the City of Kokomo to investigate the Hum.
The Acentech investigation found no evidence of ground-borne vibrations within the extremes of human perception. Its investigation of acoustic sources located two sounds that were 20 decibels above background, with frequencies of 36 and 10 hertz. The first was a cooling tower at the local DaimlerChrysler casting plant emitting a 36 hertz tone, the second was an air compressor intake at the Haynes International plant emitting a 10 hertz tone. However, even after these noises were addressed to the satisfaction of the consultant, residents still reported hearing the hum.
Auckland, New Zealand (2006)
On November 15, 2006, Dr. Tom Moir of the Massey University in Auckland, New Zealand made a recording of the Auckland Hum and has published it on the university's website. The captured Hum's power spectral density peaks at a frequency of 56 hertz. The Taos Hum was between 40 to 80 hertz. Higher-pitched tones have also been reported; the Hueytown (Alabama) Hum has been compared to the sound made by a dentist’s drill or fluorescent light bulb near the end of its life.:575
Calgary, Alberta, Canada (2008)
Investigation of the Ranchlands hum began in 2008. Marcia Epstein, an acoustic ecologist at the University of Calgary who is investigating in her spare time, said that whilst there were a variety of tones, there was a concentration of frequencies around 40 hertz, sometimes described as a "vibrational feeling", affecting "12 to 20 per cent of the community." The investigation was ongoing in 2013.
Cambridge, England, UK (2009)
The head of audiology at Addenbrooke's Hospital in Cambridge, England, Dr David Baguley, said that he believed people's problems with hum were based on the physical world about one-third of the time and the other two-thirds stemmed from people focusing too keenly on innocuous background sounds.
Windsor, Ontario, Canada (2009)
This phenomenon, first noticed in 2009, has also been reported since 2011 throughout Windsor and Essex County in Ontario, Canada. A 2011 study by Earthquakes Canada indicated that it may be originating from the heavily industrialised Zug Island area on the US side of the Detroit river. A two-hour telephone town hall meeting in 2012 received calls from 13,000 residents, with another 9,000 leaving comments over the next week, although not all of those were from people who could hear the hum.
In 2013 the Canadian Government allocated $60,000 for research by the University of Windsor to determine the source of the noise. A report released in 2014 confirmed the origin as being from Zug Island, though the precise cause of the noise has not been determined. Blast furnaces on the island may be a possible explanation. A meeting is scheduled for July 2014 with U.S. officials to discuss the study and the steps to take.
Woodland, England, UK (2011)
In June 2011, residents of the small rural village of Woodland, England reported experiencing a hum that had already lasted for over two months. It has been suggested that disused mine shafts in the area are the main culprit.
Beaufort, County Kerry, Ireland (2012)
Seattle, Washington, US (2012)
The "West Seattle Hum" in Seattle, US was first reported in the media in 2012, although residents stated that they had heard it in previous years. One suggested culprit was the mating call of the Midshipman fish, although the University of Washington researcher involved determined that this was not the case in Seattle. Local businesses from the West Marginal Way area worked with the West Seattle Blog to isolate and eliminate the noise, which was determined to be coming from equipment used to offload cargo from ships.
Wellington, New Zealand (2012)
On 8 October 2012 the city council of Wellington, New Zealand started to receive complaints about a mysterious hum. A council investigation failed to locate the source of the noise, with the investigators failing to even hear the hum. It disappeared shortly after it was first reported. The council advanced the theory that the source was a Singaporean naval vessel that had arrived in Wellington the day before the first complaint was received.
Several hypotheses are considered and discussed as possible sources of the Hum. These include cellular telephone transmissions, LORAN, HAARP, and the TACAMO aircraft operated by the US Navy for the purpose of submarine communications. Deming The Hum: An Anomalous Sound Heard Around the World
Although an obvious candidate, given the common description of the hum as sounding like a diesel engine, the majority of hums have not been traced to a specific mechanical source.
In the case of Kokomo, a city with heavy industry, the origin of the hum was thought to have been traced to two sources. The first was a 36 hertz tone from a cooling tower at the local DaimlerChrysler casting plant and the second was a 10 hertz tone from an air compressor intake at the Haynes International plant. After those devices were corrected, however, reports of the hum persisted.
However, two hums have been linked to mechanical sources. The West Seattle Hum was traced to a vacuum pump used by CalPortland to offload cargo from ships. After CalPortland replaced the silencers on the machine, reports of the hum ceased. Likewise, the Wellington Hum is thought to have been due to the diesel powered generator on a visiting ship.
A suggested diagnosis of tinnitus, a disturbance of the auditory system, is used by some physicians in response to complaints about The Hum. Tinnitus is generated internally by the auditory and nervous systems, with no external stimulus. However, the theory that the Hum is actually tinnitus fails to explain why the Hum can be heard only at certain geographical locations, to the degree those reports are accurate. There may exist individual differences as to the threshold of perception of acoustic or non-acoustic stimuli, or other normal individual variations that could contribute to the perception of the Hum by some people in the population and not by others.
While the Hum is hypothesized by some to be a form of low frequency tinnitus such as the venous hum, some sufferers claim it is not internal, being worse inside their homes than outside. However, others insist that it is equally bad indoors and outdoors. Some people notice the Hum only at home, while others hear it everywhere they go. Some sufferers report that it is made worse by soundproofing (e.g., double glazing), which serves only to decrease other environmental noise, thus making the Hum more apparent.
People who both suffer from tinnitus and hear the Hum describe them as qualitatively different, and many hum sufferers can find locations where they do not hear the hum at all. An investigation by a team of scientists in Taos dismissed the possibility that the Hum was tinnitus as highly unlikely.
Spontaneous otoacoustic emissions
Human ears generate their own noises, called spontaneous otoacoustic emissions (SOAEs), which affect between 38 percent to 60 percent of people, although the majority are unaware of these sounds. The people who hear these sounds typically hear a faint buzzing or ringing, especially if they are otherwise in complete silence. Recordings of sounds that appear to be the Hum, such as that made in Auckland, would indicate that otoacoustic emissions cannot explain all occurrences of the Hum.
On the other side has the Hum many properties similar to those attributed to SOAEs. The frequencies for both are audible to approximately 2% of the population and they tend to decrease during the years. They can be regarded as Van der Pol oscillators, which generate beats with neighboring external sounds, and may be located in places of extremely improved hearing abilities. Research indicates that both SOAEs and the Hum can be removed with a dose of 2.4g aspirin after the first day of medication, and that they can be eliminated during certain head rotations. It can be expected that the same inner ear structures are responsible for the generation of both SOAEs and the Hum. 
Colliding ocean waves
On early June, 2008 an article published in Proceedings of the Royal Society announced the location of a "hum hotspot", an "energetic source area stretching from the Labrador Sea to south of Iceland, where wind patterns are especially conducive to generating oppositely traveling waves of same period, and the ocean depth is favourable for efficient microseism generation through the ‘organ pipe’ resonance of the compression waves." Researchers from the USArray Earthscope have tracked down a series of infrasonic humming noises produced by waves crashing together and thence into the ocean floor, off the northwest coast of the US. Potentially, sound from these collisions could travel to many parts of the globe.
One of the possible causes of the West Seattle Hum considered was that it was related to the Midshipman fish. A previous hum in Sausalito, also on the west coast of the US, was determined to be the mating call of the male Midshipman. However, in that case the hum was resonating through houseboat hulls and affecting the people living on those boats. In the West Seattle case, the University of Washington researcher determined that it would be impossible for any resonating hum, transmitted via tanker or boat hulls, to be transmitted very far inland; certainly not far enough to account for the reports.
The Scottish Association for Marine Science hypothesised that the nocturnal humming sound heard in Hythe, Hampshire in the UK could be produced by a similar "sonic" fish. The council believed this to be unlikely because such fish are not commonly found in inshore waters of the UK. As of February 2014 the source had not been located, although the sound has now been recorded.
In popular culture
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- "Complaints Surround the 'Kokomo Hum'". ABC News. 13 February 2002.
- Mullins, J. H. and Kelly, J. P. The mystery of the Taos hum. Echoes, 5, 1-6, (1995). http://acousticalsociety.org/sites/default/files/docs/echoes/v5n3.pdf
- "Bondi's mystery noise maker". The Daily Telegraph (Australia). 24 May 2009.
- Deming, David (2004). "The Hum: An anomalous sound heard around the world". Journal of Scientific Exploration 18 (4): 571–594.
- "Humdinger". The Guardian. 22 July 2004.
- "Has Bristol hum mystery been solved?". Bristol Post. 20 May 2009.
- "The Buzz behind the Auckland Hum". NPR. November 22, 2006.
- "Have you heard The Hum?". Mail Online. 20 May 2009.
- Frosch, F.G. Hum and otoacoustic emissions may arise out of the same mechanisms. Journal of Scientific Exploration, 27, 603-624, (2013) http://journalofscientificexploration.org/index.php/jse/article/view/646/452
- Broner, N. (1978). "The effects of low frequency noise on people—A review". Journal of Sound and Vibration 58: 483–500. doi:10.1016/0022-460x(78)90354-1.
- Cowan, J. P. (October 2003). "The Kokomo Hum investigation". Acentech Project No. 615411 (Cambridge, MA: Accentech Incorporated).
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- "Have you heard 'the Hum'?". BBC News. 2009-05-19.
- "The Elusive Hum In Taos, New Mexico". University of New Mexico. 22 November 1995.
- "Hum Haunts Indiana City; Its Source Is a Mystery". New York Times. 23 June 2002.
- "The Kokomo Hum". Indianapolis Monthly. December 2002. pp. 157–163, 188–194.
- "Expert says hum is not a sound". Kokomo Tribune. 3 June 2004. pp. 1&12.
- "Expert says hum is not a sound". Hum Forum. 3 June 2004.
- "Auckland North Shore Hum". T.J.Moir Personal pages. 15 November 2006.
- "Mystery humming sound captured". Sydney Morning Herald. 17 November 2006.
- "Ranchlands hum eludes residents two years on". CBC News. 29 September 2011.
- "Probe of unexplained humming noise widens past Calgary". Metro (Calgary). 7 June 2013.
- "Rumblings may prompt lawsuit". Windsor Star. 5 August 2011.
- "The Sound and the Fury". OnEarth. 24 June 2013.
- "22,000 residents dial in to Windsor hum telephone town hall". Windsor Star. 23 February 2012.
- "Windsor's mysterious hum research to be funded by Ottawa". CBC News. 21 Jan 2013.
- "In search of the thing that goes hum in the night". The Independent. 18 June 2011.
- "Expert has the answer to Woodland village hums". The Advertiser Series. 23 August 2011.
- "‘The Hum’ leaves village ears ringing". Irish Examiner. 1 March 2012.
- "Locals despair as ‘The Hum’ makes life a living hell". Irish Examiner. 3 April 2012.
- "Mysterious hum in Seattle". KSDK. 6 September 2012.
- "Seattle 'Hum' May Be Due To Midshipman Fish That Produce Sound For Mating". The Huffington Post. 7 September 2012.
- "West Seattle’s now-famous ‘Hum’: Apparently NOT a fish’s fault". West Seattle Blog. 11 September 2012.
- "‘The Hum’: Ship offloading suspected in latest recurrence". West Seattle Blog. 26 September 2012.
- "‘The Hum’ followup: CalPortland installs second silencer, hopes that’s the fix". West Seattle Blog. 7 December 2012.
- "Wellington 'hum' becomes nationwide obsession". 3 News. 11 October 2012.
- "Wellington hum disappears". 3 News. 16 October 2012.
- "Singapore's frigate 'Stalwart' source of Wellington hum?". 3 News. 11 October 2012.
- "The Phenomenon of Low Frequency Hums". Norfolk Tinnitus Society. 1993.
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- Abrams, M. An Inescapable Buzz. Discover Magazine. October 1995.
- Sharon Kedar et al. (8 March 2008). "The origin of deep ocean microseisms in the North Atlantic Ocean". Proceedings of the Royal Society (Royal Society Publishing) 464 (2091): 777–793. Bibcode:2008RSPSA.464..777K. doi:10.1098/rspa.2007.0277.
- "Ocean 'hum' hotspot located". Nature. 8 January 2008.
- "Scientists Track Down Source of Earth’s Hum". Wired. August 7, 2009.
- "Coasts confirmed as main source of Earth's 'hum'". Physics World. 10 July 2009.
- "Humming Toadfish Are the Buzz of Sausalito". NBC. 16 June 1986.
- "Mystery hum keeping people awake may be love-making fish". The Telegraph. 23 October 2013.
- "Southampton Water mystery droning prompts more moaning". BBC News. 24 October 2013.
- "Minutes of a meeting of the New Forest Environmental Protection Liaison Committee". New Forest District Council. 7 February 2014. p. 4.
- "Unsolved Mysteries: Ghosts (2005)". Amazon.com. Disc 4, "Mystery Hum".
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- "In A Tiny English Town, A 'Hum' Pierces Each Night". NPR. 15 June 2011.
- ""Drive"". Ten Thirteen Productions. The X Files. November 15, 1998. Event occurs at 40:00.
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- Moorhouse, Andy; Waddington, David; Adams, Mags (February 2005). "Procedure for the assessment of low frequency noise complaints". Acoustics Research Centre, University of Salford.
- Tanimoto, Toshiro (2008). "Geophysics: Humming a different tune". Nature 452 (539).