Page 32 - Volume 9, Issue 3

Gavreau made misleading statements, which led to confusion of harmful effects of very high levels at higher frequencies with the effects of infrasound.
For example from the 1968 paper on “Infrasound,” which was published in a popular science journal: (Gavreau 1968):
Infrasounds are not difficult to study but they are potentially harmful. For example one of my col- leagues, R Levavasseur, who designed a powerful emitter known as the ‘Levavasseur whistle’ is now a victim of his own inventiveness. One of his larger whistles emitting at 2600Hz had an acoustic power of 1kW... This proved sufficient to make him a life- long invalid.
Of course, 2600Hz is not infrasound, but the misleading implication is that infrasound caused injury to Levavasseur.
Gavreau’s progress
Gavreau energized his sources in a laboratory, exposing himself and his co-workers to very high levels of noise at rel- atively high frequencies. For example at 196Hz from a pneu- matic “whistle” and 37Hz from a larger whistle. Exposure to the 196Hz source at a level of 160dB led to irritation of inter- nal organs, so that Gavreau and his colleague felt unwell fol- lowing a five minute exposure. Again from the 1968 paper:
manner in which it was described. Much of the paper with the title “Infrasound” is not about infrasound. The work was picked up by the media and embellished further, including claims that 7Hz is fatal.
The misunderstanding between infrasound and low fre- quency noise continues. A newspaper article on low frequen- cy noise from wind turbines (Miller 24 January 2004), opens with: “Onshore wind farms are a health hazard to people liv- ing near them because of the low-frequency noise that they emit, according to new medical studies.”
A French translation of this article for use by objector groups opens with: “De nouvelles études médicales indiquent que les éoliennes terrestres représentent un risque pour la santé des gens habitant à proximité, à cause de l’émission d’infra- sons.”
The translation of low frequency noise into infrasons con- tinues through the article. This is not a trivial misrepresenta- tion because, following on from Gavreau, infrasound has been connected with many misfortunes, being blamed for problems for which some other explanation had not yet been found (e.g., brain tumors, sudden infant deaths, road acci- dents). A selection of some UK press headlines from the early years is:
The Silent Sound Menaces Drivers - Daily Mirror, 19th October 1969
Does Infrasound Make Drivers Drunk? - New Scientist, 16th March 1972
Brain Tumours ‘caused by noise’ - The Times, 29th September 1973
Crowd Control by Light and Sound - The Guardian, 3rd October 1973
Danger in Unheard Car Sounds - The Observer, 21st April 1974
The Silent Killer All Around Us - Evening News, 25th May 1974
Noise is the Invisible Danger - Care on the Road
(ROSPA) August 1974
Infrasound and low frequency noise are often associated in the public mind with the “hum.” This is mystery noise of unknown origin, which is heard periodically by a few people, and causes them great distress, but is difficult to measure. The hum has been reviewed by Demming, who gives refer- ences to North American occurrences (Demming 2004). Demming has established a Yahoo Group Hum Forum, <http://tech.groups.yahoo.com/group/humforum/>, to help hum sufferers interact and support each other.
Absurd statements were made in the book Supernature by Lyall Watson, first published in 1973 as A Natural History of the Supernatural and which has had a number of reprints and large sales. This book includes an extreme instance of the incredible nonsense which has been published about infra- sound. It states that the technician who gave the first trial blast of Gavreau’s whistle “fell down dead on the spot.” A post mortem showed that “all his internal organs had been mashed into an amorphous jelly by the vibrations.” It contin- ues that, in a controlled experiment, all the windows were broken within a half mile of the test site and further, that two infrasonic generators “focused on a point even five miles
... after the test we became aware of a painful ‘reso- nance’ within our bodies – everything inside us seemed to vibrate when we spoke or moved. What had happened was that this sound at 160 decibels... acting directly on the body produced intense fric- tion between internal organs, resulting in severe irritation of the nerve endings. Presumably if the test had lasted longer than five minutes, internal hemorrhage would have occurred.
196 Hz is not infrasound, but the unpleasant effects described in a paper with the title “Infrasound.”
are
The 37Hz whistle was run at a low level, but sufficient to cause the lightweight walls of the laboratory to vibrate. Some of Gavreau’s earlier work had been in the development of pneumatic high intensity ultrasonic sources, so that he mere- ly had to scale up the size for low frequency operation.
Gavreau also generated 7Hz with a tube of length 24m, driven by either a loudspeaker or a motor- driven piston. He suggested that 7Hz was particularly “dangerous” because the frequency coincided with alpha rhythms of the brain. He also
used a tube to generate 3.5Hz, but further details were given.
And from the 1968 paper:
The effects of low frequency sound and infrasound are noxious. However, we found one exception: the intense vibration of the nasal cavities produced by our whistle (340Hz, 155 decibels) had favorable effects! In one case, a subject recovered a sense of smell which he had lost some years back and was able to breathe more easily.
Infrasound and the public
not
By present standards, Gavreau’s work was irresponsible, both in the manner in which it was carried out and in the
Concerns About Infrasound from Wind Turbines 31