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Infrasound

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Infrasound arrays at monitoring station in Qaanaaq, Greenland.

Infrasound, sometimes referred to as low frequency sound or subsonic, describes sound waves with a frequency below the lower limit of human audibility (generally 20 Hz, as defined by the ANSI/ASA S1.1-2013 standard).[1] Hearing becomes gradually less sensitive as frequency decreases, so for humans to perceive infrasound, the sound pressure must be sufficiently high. Although the ear is the primary organ for sensing low sound, at higher intensities it is possible to feel infrasound vibrations in various parts of the body.

The study of such sound waves is sometimes referred to as infrasonics, covering sounds beneath 20 Hz down to 0.1 Hz (and rarely to 0.001 Hz). People use this frequency range for monitoring earthquakes and volcanoes, charting rock and petroleum formations below the earth, and also in ballistocardiography and seismocardiography to study the mechanics of the human cardiovascular system.

Infrasound is characterized by an ability to get around obstacles with little dissipation. In music, acoustic waveguide methods, such as a large pipe organ or, for reproduction, exotic loudspeaker designs such as transmission line, rotary woofer, or traditional subwoofer designs can produce low-frequency sounds, including near-infrasound. Subwoofers designed to produce infrasound are capable of sound reproduction an octave or more below that of most commercially available subwoofers, and are often about 10 times the size.[citation needed]

History and study

[edit]

One of the pioneers in infrasonic research was French scientist Vladimir Gavreau.[2] His interest in infrasonic waves first came about in 1957 in the large concrete building that he and his research team were working in. The group was experiencing bouts of periodic and deeply unpleasant nausea. After weeks of speculation on the source of the nausea — the team was convinced that it was a pathogen or an untraced leak of noxious chemical fumes in the facility — they discovered that a "loosely poised low speed motor... was developing [these] 'nauseating vibrations'".[2]

When Gavreau and the team attempted to measure an amplitude and pitch, they were shocked when their equipment detected no audible sound. They concluded the sound being generated by the motor was so low in pitch that it was below their biological ability to hear, and that their recording equipment was not capable of detecting these frequencies. Nobody had conceived that sound might exist at such low frequencies, and so no equipment had been developed to detect it. Eventually, it was determined that the sound inducing the nausea was a 7 cycle per second infrasound wave that was inducing a resonant mode in the ductwork and architecture of the building, significantly amplifying the sound.[2] In the wake of this serendipitous discovery, the researchers soon got to work preparing further infrasonic tests in the laboratories. One of his experiments was an infrasonic whistle, an oversized organ pipe.[3][4][5] As a result of this and similar incidents, it has become routine in new architecture construction to inspect for and eliminate any infrasonic resonances in cavities and the introduction of sound-proofing and materials with specialized sonic properties.

Sources

[edit]
Patent for a double bass reflex loudspeaker enclosure design intended to produce infrasonic frequencies ranging from 5 to 25 hertz, of which traditional subwoofer designs are not readily capable.

Infrasound can result from both natural and man-made sources:

  • Human singers: some vocalists, including Tim Storms, can produce notes in the infrasound range.[30]

Animal reaction

[edit]
Main article: Perception of infrasound
Further information: Tsunami § Possible animal reaction, and Rayleigh wave § Possible animal reaction

Some animals have been thought to perceive the infrasonic waves going through the earth, caused by natural disasters, and to use these as an early warning. An example of this is the 2004 Indian Ocean earthquake and tsunami. Animals were reported to have fled the area hours before the actual tsunami hit the shores of Asia.[34][35] It is not known for sure that this is the cause; some have suggested that it may have been the influence of electromagnetic waves, and not of infrasonic waves, that prompted these animals to flee.[36]

Research in 2013 by Jon Hagstrum of the US Geological Survey suggests that homing pigeons use low-frequency infrasound to navigate.[37]

Human reactions

[edit]
Further information: Health effects from noise

20 Hz is considered the normal low-frequency limit of human hearing. When pure sine waves are reproduced under ideal conditions and at very high volume, a human listener will be able to identify tones as low as 12 Hz.[38] Below 10 Hz it is possible to perceive the single cycles of the sound, along with a sensation of pressure at the eardrums.

From about 1000 Hz, the dynamic range of the auditory system decreases with decreasing frequency. This compression is observable in the equal-loudness-level contours, and it implies that even a slight increase in level can change the perceived loudness from barely audible to loud. Combined with the natural spread in thresholds within a population, its effect may be that a very low-frequency sound which is inaudible to some people may be loud to others.[citation needed]

One study has suggested that infrasound may cause feelings of awe or fear in humans. It has also been suggested that since it is not consciously perceived, it may make people feel vaguely that odd or supernatural events are taking place.[39]

A scientist working at Sydney University's Auditory Neuroscience Laboratory reports growing evidence that infrasound may affect some people's nervous system by stimulating the vestibular system, and this has shown in animal models an effect similar to sea sickness.[40]

In research conducted in 2006 focusing on the impact of sound emissions from wind turbines on the nearby population, perceived infrasound has been associated to effects such as annoyance or fatigue, depending on its intensity, with little evidence supporting physiological effects of infrasound below the human perception threshold.[41] Later studies, however, have linked inaudible infrasound to effects such as fullness, pressure or tinnitus, and acknowledged the possibility that it could disturb sleep.[42] Other studies have also suggested associations between noise levels in turbines and self-reported sleep disturbances in the nearby population, while adding that the contribution of infrasound to this effect is still not fully understood.[43][44]

In a study at Ibaraki University in Japan, researchers said EEG tests showed that the infrasound produced by wind turbines was "considered to be an annoyance to the technicians who work close to a modern large-scale wind turbine".[45][46][47]

Jürgen Altmann of the Technical University of Dortmund, an expert on sonic weapons, has said that there is no reliable evidence for nausea and vomiting caused by infrasound.[48]

High volume levels at concerts from subwoofer arrays have been cited as causing lung collapse in individuals who are very close to the subwoofers, especially for smokers who are particularly tall and thin.[49]

In September 2009, London student Tom Reid died in a club of sudden arrhythmic death syndrome (SADS) after complaining that "loud bass notes" from the club's speakers 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.[50]

Air is a very inefficient medium for transferring low frequency vibration from a transducer to the human body.[51] 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 surrounding the "brown note" and its effects.[52][53][clarification needed]

The report "A Review of Published Research on Low Frequency Noise and its Effects"[54] contains a long list of research about exposure to high-level infrasound among humans and animals. For instance, in 1972, Borredon exposed 42 young men to tones at 7.5 Hz at 130 dB for 50 minutes. This exposure caused no adverse effects other than reported drowsiness and a slight blood pressure increase. In 1975, Slarve and Johnson exposed four male subjects to infrasound at frequencies from 1 to 20 Hz, for eight minutes at a time, at levels up to 144 dB SPL. There was no evidence of any detrimental effect other than middle ear discomfort. Tests of high-intensity infrasound on animals resulted in measurable changes, such as cell changes and ruptured blood vessel walls.

Infrasound is one hypothesized cause of death for the nine Soviet hikers who were found dead at Dyatlov Pass in 1959.[55]


Hygienic standards in the workplace

[edit]

US: Maximum levels for frequencies from 1 to 80 Hz are no more than 145 dB. Overall level (for all frequencies) - no more than 150 dB.[56]

Brown note

[edit]
Main article: Brown note

The brown note is a hypothetical infrasonic frequency capable of causing fecal incontinence by creating acoustic resonance in the human bowel. Attempts to demonstrate the existence of a "brown note" using sound waves transmitted through the air have failed.

In February 2005 the television show MythBusters attempted to verify whether the "brown note" was a reality. They tested notes down to 5 Hz in frequency and up to 153 dB in sound pressure. They used a type subwoofer used for major rock concerts, and which had been specially modified for deeper bass extension. The rumored physiological effects did not materialize. The show declared the brown note myth "busted."[58][59][60][61]

Infrasonic 17 Hz tone experiment

[edit]

On 31 May 2003, a group of UK researchers held a mass experiment, where they exposed some 700 people to music laced with soft 17 Hz sine waves played at a level described as "near the edge of hearing", produced by an extra-long-stroke subwoofer mounted two-thirds of the way from the end of a seven-meter-long plastic sewer pipe. The experimental concert (entitled Infrasonic) took place in the Purcell Room over the course of two performances, each consisting of four musical pieces. Two of the pieces in each concert had 17 Hz tones played underneath.[62][63]

In the second concert, the pieces that were to carry a 17 Hz undertone were swapped so that test results would not focus on any specific musical piece. The participants were not told which pieces included the low-level 17 Hz near-infrasonic tone. The presence of the tone resulted in a significant number (22%) of respondents reporting feeling uneasy or sorrowful, getting chills down the spine or nervous feelings of revulsion or fear.[62][63]

In presenting the evidence to the British Association for the Advancement of Science, Professor Richard Wiseman said "These results suggest that low frequency sound can cause people to have unusual experiences even though they cannot consciously detect infrasound. Some scientists have suggested that this level of sound may be present at some allegedly haunted sites and so cause people to have odd sensations that they attribute to a ghost—our findings support these ideas."[39]

Suggested relationship to ghost sightings

[edit]

Psychologist Richard Wiseman of the University of Hertfordshire suggests that the odd sensations that people attribute to ghosts may be caused by infrasonic vibrations. Vic Tandy, experimental officer and part-time lecturer in the school of international studies and law at Coventry University, along with Dr. Tony Lawrence of the University's psychology department, wrote in 1998 a paper called "Ghosts in the Machine" for the Journal of the Society for Psychical Research. Their research suggested that an infrasonic signal of 19 Hz might be responsible for some ghost sightings. Tandy was working late one night alone in a supposedly haunted laboratory at Warwick, when he felt very anxious and could detect a grey blob out of the corner of his eye. When Tandy turned to face the grey blob, there was nothing.

The following day, Tandy was working on his fencing foil, with the handle held in a vice. Although there was nothing touching it, the blade started to vibrate wildly. Further investigation led Tandy to discover that the extractor fan in the lab was emitting a frequency of 18.98 Hz, very close to the resonant frequency of the eye given as 18 Hz by NASA.[64] This, Tandy conjectured, was why he had seen a ghostly figure—it was, he believed, an optical illusion caused by his eyeballs resonating. The room was exactly half a wavelength in length, and the desk was in the centre, thus causing a standing wave which caused the vibration of the foil.[65]

Tandy investigated this phenomenon further and wrote a paper entitled The Ghost in the Machine.[66] He carried out a number of investigations at various sites believed to be haunted, including the basement of the Tourist Information Bureau next to Coventry Cathedral[67][68] and Edinburgh Castle.[69][70]

Detection and measurement

[edit]

NASA Langley has designed and developed an infrasonic detection system that can be used to make useful infrasound measurements at a location where it was not possible previously. The system comprises an electret condenser microphone PCB Model 377M06, having a 3-inch membrane diameter, and a small, compact windscreen.[71] Electret-based technology offers the lowest possible background noise, because Johnson noise generated in the supporting electronics (preamplifier) is minimized.[71]

The microphone features a high membrane compliance with a large backchamber volume, a prepolarized backplane and a high impedance preamplifier located inside the backchamber. The windscreen, based on the high transmission coefficient of infrasound through matter, is made of a material having a low acoustic impedance and has a sufficiently thick wall to ensure structural stability.[72] Close-cell polyurethane foam has been found to serve the purpose well. In the proposed test, test parameters will be sensitivity, background noise, signal fidelity (harmonic distortion), and temporal stability.

The microphone design differs from that of a conventional audio system in that the peculiar features of infrasound are taken into account. First, infrasound propagates over vast distances through the Earth's atmosphere as a result of very low atmospheric absorption and of refractive ducting that enables propagation by way of multiple bounces between the Earth's surface and the stratosphere. A second property that has received little attention is the great penetration capability of infrasound through solid matter – a property utilized in the design and fabrication of the system windscreens.[72]

Thus the system fulfills several instrumentation requirements advantageous to the application of acoustics: (1) a low-frequency microphone with especially low background noise, which enables detection of low-level signals within a low-frequency passband; (2) a small, compact windscreen that permits (3) rapid deployment of a microphone array in the field. The system also features a data acquisition system that permits real time detection, bearing, and signature of a low-frequency source.[72]

Infrasound for nuclear detonation detection

[edit]

Infrasound is one of several techniques used to identify if a nuclear detonation has occurred. A network of 60 infrasound stations, in addition to seismic and hydroacoustic stations, comprise the International Monitoring System (IMS) that is tasked with monitoring compliance with the Comprehensive Nuclear Test-Ban Treaty (CTBT).[73] IMS Infrasound stations consist of eight microbarometer sensors and space filters arranged in an array covering an area of approximately 1 to 9 km2.[73][74] The space filters used are radiating pipes with inlet ports along their length, designed to average out pressure variations like wind turbulence for more precise measurements.[74] The microbarometers used are designed to monitor frequencies below approximately 20 hertz.[73] Sound waves below 20 hertz have longer wavelengths and are not easily absorbed, allowing for detection across large distances.[73]

Infrasound wavelengths can be generated artificially through detonations and other human activity, or naturally from earthquakes, severe weather, lightning, and other sources.[73] Like forensic seismology, algorithms and other filter techniques are required to analyze gathered data and characterize events to determine if a nuclear detonation has actually occurred. Data is transmitted from each station via secure communication links for further analysis. A digital signature is also embedded in the data sent from each station to verify if the data is authentic.[75]

The Comprehensive Nuclear-Test-Ban Treaty Organization Preparatory Commission uses infrasound as one of its monitoring technologies, along with seismic, hydroacoustic, and atmospheric radionuclide monitoring. The loudest infrasound recorded to date by the monitoring system was generated by the 2013 Chelyabinsk meteor.[76]

[edit]

The 2017 film The Sound uses infrasound as a major plot element.[77][78]

In "Fermata", a 2020 episode of the Franco-Belgian TV series Astrid et Raphaëlle, infrasound from a generator hidden in the pipe organ of the Grand Auditorium in the Maison de la Radio et de la Musique, the Paris headquarters of Radio France, is used as a murder weapon.

The 'ghost frequency' phenomenon is mentioned in Season 3 Episode 4 of the TV Series Evil, The Demon of the Road.

See also

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References

[edit]
Notes
  1. ^ "A Study of Low Frequency Noise and Infrasound from Wind Turbines" (PDF). Ia.cpuc.ca.gov. Retrieved 12 March 2022.
  2. ^ a b c "Gavreau", in Lost Science Archived 19 February 2012 at the Wayback Machine by Gerry Vassilatos. Signals, 1999. ISBN 0-932813-75-5
  3. ^ Gavreau V., Infra Sons: Générateurs, Détecteurs, Propriétés physiques, Effets biologiques, in: Acustica, vol. 17, no. 1 (1966), pp. 1–10
  4. ^ Gavreau V., infrasound, in: Science journal 4(1) 1968, p. 33
  5. ^ Gavreau V., "Sons graves intenses et infrasons" in: Scientific Progress – la Nature (Sept. 1968) pp. 336–344
  6. ^ Garces, M.; Hetzer C.; Merrifield M.; Willis M.; Aucan J. (2003). "Observations of surf infrasound in Hawai'i". Geophysical Research Letters. 30 (24): 2264. Bibcode:2003GeoRL..30.2264G. doi:10.1029/2003GL018614. S2CID 42665337. Comparison of ocean buoy measurements with infrasonic array data collected during the epic winter of 2002–2003 shows a clear relationship between breaking ocean wave height and infrasonic signal levels.
  7. ^ Fee, David; Matoza, Robin S. (1 January 2013). "An overview of volcano infrasound: From hawaiian to plinian, local to global". Journal of Volcanology and Geothermal Research. 249: 123–139. Bibcode:2013JVGR..249..123F. doi:10.1016/j.jvolgeores.2012.09.002. ISSN 0377-0273.
  8. ^ Johnson, Jeffrey Bruce; Ripepe, Maurizio (15 September 2011). "Volcano infrasound: A review". Journal of Volcanology and Geothermal Research. 206 (3): 61–69. Bibcode:2011JVGR..206...61J. doi:10.1016/j.jvolgeores.2011.06.006. ISSN 0377-0273.
  9. ^ Garces, M.; Willis, M. (2006). Modeling and Characterization of Microbarom Signals in the Pacific (Report). Archived from the original on 11 February 2009. Retrieved 24 November 2007. Naturally occurring sources of infrasound include (but are not limited to) severe weather, volcanoes, bolides, earthquakes, mountain waves, surf, and, the focus of this research, nonlinear ocean wave interactions.
  10. ^ Haak, Hein (1 September 2006). "Probing the Atmosphere with Infrasound : Infrasound as a tool" (PDF). CTBT: Synergies with Science, 1996–2006 and Beyond. Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization. Archived from the original (PDF) on 2 July 2007.
  11. ^ "Microbaroms". Infrasonic Signals. University of Alaska Fairbanks, Geophysical Institute, Infrasound Research Group. Archived from the original on 15 February 2008. Retrieved 22 November 2007. The ubiquitous five-second-period infrasonic signals called "microbaroms", which are generated by standing sea waves in marine storms, are the cause of the low-level natural-infrasound background in the passband from 0.02 to 10 Hz.
  12. ^ "NOAA ESRL Infrasonics Program". Archived from the original on 8 April 2020. Retrieved 10 April 2012.
  13. ^ Payne, Katharine B.; Langbauer, William R.; Thomas, Elizabeth M. (1986). "Infrasonic calls of the Asian elephant (Elephas maximus)". Behavioral Ecology and Sociobiology. 18 (4): 297–301. doi:10.1007/BF00300007. S2CID 1480496.
  14. ^ Barklow, William E. (2004). "Low-frequency sounds and amphibious communication in Hippopotamus amphibious". Journal of the Acoustical Society of America. 115 (5): 2555. Bibcode:2004ASAJ..115.2555B. doi:10.1121/1.4783854. Archived from the original on 8 February 2013.
  15. ^ von Muggenthaler, E.K.; Stoughton, J.W.; Daniel, J.C., Jr. (1993). "Infrasound from the rhinocerotidae". In Ryder, O.A. (ed.). Rhinoceros biology and conservation: Proceedings of an international conference, San Diego, U.S.A. Zoological Society of San Diego. pp. 136–140.
  16. ^ a b von Muggenthaler, Elizabeth (2003). "Songlike vocalizations from the Sumatran Rhinoceros (Dicerorhinus sumatrensis)". Acoustics Research Letters Online. 4 (3): 83. doi:10.1121/1.1588271.
  17. ^ Marrin, West (3 November 2004). Infrasonic signals in the environment (PDF). Acoustics 2004: Transportation Noise & Vibration — The New Millennium. Gold Coast, Australia: Australian Acoustical Society. Archived from the original (PDF) on 26 March 2012.
  18. ^ von Muggenthaler, E.; Baes, C.; Hill, D.; Fulk, R.; Lee, A. (1999). Infrasound and low frequency vocalizations from the giraffe; Helmholtz resonance in biology. Riverbanks Consortium on biology and behavior. Archived from the original on 15 February 2012.
  19. ^ E. Von Muggenthaler: Infrasound from the okapi, invited presentation, student competition award, proceedings from the 1992 American Association for the Advancement of Science (A.A.A.S) 158th conference, 1992
  20. ^ Freeman, Angela R.; Hare, James F. (1 April 2015). "Infrasound in mating displays: a peacock's tale". Animal Behaviour. 102: 241–250. doi:10.1016/j.anbehav.2015.01.029. ISSN 0003-3472. S2CID 53164879.
  21. ^ Work by Muggenthaler et al, also referred to in: The Secret Of A Tiger's Roar, ScienceDaily, 1 December 2000, American Institute of Physics, Inside Science News Service (1 December 2000), Retrieved 25 December 2011
  22. ^ Von Muggenthaler, E., Perera, D. (2002), The cat's purr: a healing mechanism?, In review, presented 142nd Acoustical Society of America International Conference, 2001.
  23. ^ Work by Muggenthaler et al, referred to in: David Harrison: Revealed: how purrs are secret to cats' nine lives, The Telegraph, 18 March 2001, Retrieved 25 December 2011
  24. ^ von Muggenthaler, (2006) The Felid Purr: A Biomechanical Healing Mechanism, Proceedings from the 12th International Low Frequency Noise and Vibration Conference, pp. 189–208
  25. ^ "Science Question of the Week - 07 April 2000". 2 November 2004. Archived from the original on 2 November 2004. Retrieved 12 March 2022.
  26. ^ Langbauer, W.R.; Payne, K.B.; Charif, R.A.; Rapaport, L.; Osborn, F. (1991). "African elephants respond to distant playbacks of low-frequency conspecific calls" (PDF). The Journal of Experimental Biology. 157 (1): 35–46. doi:10.1242/jeb.157.1.35. Retrieved 27 May 2009.
  27. ^ W. John Richardson; Charles R. Greene, Jr.; Charles I. Malme; Denis H. Thomson (1995). Marine Mammals and Noise. Academic Press. ISBN 978-0-12-588440-2.
  28. ^ Larom, D.; Garstang, M.; Payne, K.; Raspet, R.; Lindeque, M. (1997). "The influence of surface atmospheric conditions on the range and area reached by animal vocalizations" (PDF). The Journal of Experimental Biology. 200 (3): 421–431. doi:10.1242/jeb.200.3.421. PMID 9057305. Retrieved 27 May 2009.
  29. ^ Garstang, Michael (1 January 2010), Brudzynski, Stefan M. (ed.), "Chapter 3.2 - Elephant infrasounds: long-range communication", Handbook of Behavioral Neuroscience, Handbook of Mammalian Vocalization, vol. 19, Elsevier, pp. 57–67, doi:10.1016/B978-0-12-374593-4.00007-3, retrieved 27 January 2020
  30. ^ Hsu, Christine (24 August 2012). "Man With World's Deepest Voice Hits Notes That Only Elephants Can Hear". Medical Daily. Retrieved 2 August 2016. American singer Tim Storms who also has the world's widest vocal range can reach notes as low as G-7 (0.189Hz) [...] so low that even Storms himself cannot hear it.
  31. ^ Chen, C.H., ed. (2007). Signal and Image Processing for Remote Sensing. Boca Raton: CRC. p. 33. ISBN 978-0-8493-5091-7.
  32. ^ "Data-Bass". Data-bass.com. Archived from the original on 9 May 2016. Retrieved 12 May 2016.
  33. ^ "The Reference's — IMF electronics". Imf-elecctronics.com. Archived from the original on 27 October 2014. Retrieved 27 October 2014.
  34. ^ Malone, Elizabeth; Deretsky, Zina. "After the tsunami". National Science Foundation. Archived from the original on 24 November 2017. Retrieved 26 December 2011.
  35. ^ Kenneally, Christine (30 December 2004). "How did animals survive the tsunami?". Slate Magazine.
  36. ^ "Can Animals Predict Disaster?". Pbs.org. 5 June 2008. Retrieved 12 March 2022.
  37. ^ Knight, Kathryn (15 February 2013). "Disappearing Homing Pigeon Mystery Solved". Journal of Experimental Biology. 216 (4): i. doi:10.1242/jeb.085506. S2CID 86492016.
  38. ^ Olson, Harry F. (1967). Music, Physics and Engineering. Dover Publications. p. 249. ISBN 978-0-486-21769-7.
  39. ^ a b "Infrasound linked to spooky effects". NBC News. 7 September 2003.
  40. ^ King, Simon (12 June 2015). "Wind farm effect on balance 'akin to seasickness': scientist". News Corp Australia.
  41. ^ Rogers, Anthony; Manwell, James (2006). "Wright". Sally: 9. CiteSeerX 10.1.1.362.4894.
  42. ^ Salt, Alec N.; Kaltenbach, James A. (19 July 2011). "Infrasound From Wind Turbines Could Affect Humans". Bulletin of Science, Technology & Society. 31 (4): 296–302. doi:10.1177/0270467611412555. S2CID 110190618.
  43. ^ Abbasi, Milad; Monnazzam, Mohammad Reza; Zakerian, SayedAbbolfazl; Yousefzadeh, Arsalan (June 2015). "Effect of Wind Turbine Noise on Workers' Sleep Disorder: A Case Study of Manjil Wind Farm in Northern Iran". Fluctuation and Noise Letters. 14 (2): 1550020. Bibcode:2015FNL....1450020A. doi:10.1142/S0219477515500200.
  44. ^ Bolin, Karl; Bluhm, Gösta; Eriksson, Gabriella; Nilsson, Mats E (1 July 2011). "Infrasound and low frequency noise from wind turbines: exposure and health effects". Environmental Research Letters. 6 (3): 035103. Bibcode:2011ERL.....6c5103B. doi:10.1088/1748-9326/6/3/035103.
  45. ^ "Wind-farm workers suffer poor sleep, international studies find". The Australian.
  46. ^ Abbasi, Milad; Monnazzam, Mohammad Reza; Zakerian, Sayedabbolfazl; Yousefzadeh, Arsalan (2015). "Effect of Wind Turbine Noise on Workers' Sleep Disorder: A Case Study of Manjil Wind Farm in Northern Iran". Fluctuation and Noise Letters. 14 (2): 1550020. Bibcode:2015FNL....1450020A. doi:10.1142/S0219477515500200.
  47. ^ Inagaki, T.; Li, Y.; Nishi, Y. (10 April 2014). "Analysis of aerodynamic sound noise generated by a large-scaled wind turbine and its physiological evaluation". International Journal of Environmental Science and Technology. 12 (6): 1933–1944. doi:10.1007/s13762-014-0581-4. S2CID 56410935.
  48. ^ The Pentagon considers ear-blasting anti-hijack gun — New Scientist
  49. ^ "Music Fans, Beware the Big Bass". Wired. 2 September 2004. Retrieved 12 March 2022.
  50. ^ "Loud bass music 'killed student' Tom Reid". Metro. 9 December 2009. Retrieved 12 March 2022.
  51. ^ Rood, G. (1 August 1977). "Book Review: Infrasound and low frequency vibration. 1977, W. Tempest. London: Academic Press Inc. (London) Ltd". Journal of Sound and Vibration. 53 (4): 605–606. Bibcode:1977JSV....53..605R. doi:10.1016/0022-460X(77)90533-8. Retrieved 12 March 2022.
  52. ^ ProSoundWeb: some effects of low end (bulletin board entry by Tom Danley)
  53. ^ "Matterhorn". 13 January 2008. Archived from the original on 13 January 2008. Retrieved 12 March 2022.
  54. ^ "A Review of Published Research on Low Frequency Noise and its Effects" (PDF). Defra.gov.uk. Archived from the original (PDF) on 20 September 2008. Retrieved 11 January 2022.
  55. ^ "Return to Dead Mountain;— Kármán vortex street, infrasound at Dyatlov Pass". failuremag.com. 1 February 2014. Archived from the original on 22 January 2022.
  56. ^ "Acoustic — Infrasound and Low-Frequency Sound". 2020 TLVs and BEIs Book. Cincinnati, Ohio: American Conference of Governmental Industrial Hygienists. 2020. pp. 126–127. ISBN 978-1-607261-12-4.
  57. ^ "§ 35, Table 5.5". State hygienic requirements 1.2.3685-21 "Hygienic requirements for the safety of environmental factors for humans" [СанПиН 1.2.3685-21 "Гигиенические нормативы и требования к обеспечению безопасности и (или) безвредности для человека факторов среды обитания"] (in Russian). Moscow: Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing. 2021. p. 338. Retrieved 4 July 2024.
  58. ^ "Brown Note | MythBusters". Discovery. 11 April 2012. Retrieved 29 May 2016.
  59. ^ "Brown Note". Meyer Sound. 2000. Archived from the original on 6 September 2006. Retrieved 30 August 2006.
  60. ^ "Meyer Sound 700-HP UltraHigh-Power Subwoofer datasheet" (PDF). Archived from the original (PDF) on 21 October 2007. Retrieved 14 November 2007.
  61. ^ "Meyer Sound Gets Down to Basics in MythBusters Episode". Meyer Sound Laboratories. September 2004. Archived from the original on 14 July 2011. Retrieved 1 September 2010.
  62. ^ a b Infrasonic concert, Purcell Room, London, 31 May 2003, sponsored by the sciart Consortium with additional support by the National Physical Laboratory (NPL)
  63. ^ a b "Sounds like terror in the air". The Sydney Morning Herald. 9 September 2003. Retrieved 12 March 2022.
  64. ^ NASA Technical Report 19770013810, Dtic.mil
  65. ^ "infrasound — The Skeptic's Dictionary". Skepdic.com. Retrieved 12 March 2022.
  66. ^ Tandy, V.; Lawrence, T. (April 1998). "The ghost in the machine" (PDF). Journal of the Society for Psychical Research. 62 (851): 360–364.
  67. ^ Tandy, V. (July 2000). "Something in the cellar" (PDF). Journal of the Society for Psychical Research. 64.3 (860). Archived from the original (PDF) on 29 September 2011.
  68. ^ Arnot, Chris (11 July 2000). "Ghost buster". The Guardian. London.
  69. ^ Who ya gonna call? Vic Tandy! – Coventry Telegraph Archived 1 May 2011 at the Wayback Machine
  70. ^ "The Ghost Experiment — theories, infrasound". 19 January 2007. Archived from the original on 19 January 2007. Retrieved 12 March 2022.
  71. ^ a b Development and installation of an infrasonic wake vortex detection system By Qamar A. Shams and Allan J. Zuckerwar, NASA Langley Research Center, Hampton VA USA, WakeNet-Europe 2014, Bretigny, France.
  72. ^ a b c Atkinson, Joe (25 July 2014). "NASA Langley Researchers Nab Invention of the Year for Infrasound Detection System". NASA Langley Research Center. Archived from the original on 27 October 2014.
  73. ^ a b c d e "IMS Infrasound Network". can-ndc.nrcan.gc.ca. Natural Resources Canada. 30 March 2020. Retrieved 25 April 2017.
  74. ^ a b "Infrasound Monitoring". Ga.gov.au. 15 May 2014. Retrieved 25 April 2017.
  75. ^ "Infrasound monitoring". Ctbto.org. CTBTO Preparatory Commission. Archived from the original on 3 February 2017. Retrieved 25 April 2017.
  76. ^ Harper, Paul (20 February 2013). "Meteor explosion largest infrasound recorded". The New Zealand Herald. APN Holdings NZ. Retrieved 31 March 2013.
  77. ^ Lowe, Justin (3 October 2017). "'The Sound': Film Review". The Hollywood Reporter. Retrieved 29 March 2021. Continuing her search, Kelly soon encounters ghostly apparitions and overwhelming low-frequency sound waves below the threshold of human hearing that emanate from a source she's unable to identify with her audio gear.
  78. ^ Kermode, Jennie (27 September 2017). "The Sound (2017) Movie Review from Eye for Film". Eye For Film. Retrieved 29 March 2021.
Bibliography
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Look up infrasound in Wiktionary, the free dictionary.
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