Anxiety over “wind-turbine syndrome” stems from a decades-old misunderstanding of inaudible noise.

In his 1973 book Supernature, the scientist and adventurer Lyall Watson tells the story of a six-foot-long whistle. Part of an experiment in the 1960s, the enormous device was designed to explore the effects of low-frequency sound on humans. The technician who first tested it “fell down dead on the spot,” Watson writes. “His internal organs had been mashed into an amorphous jelly.”

How could such a gruesome death result from sound? While scientifically dubious, the idea that low-frequency noises can do extreme damage to people has been popular for decades. Infrasound—sound that’s commonly (and incorrectly) thought to be below the threshold for human hearing—has often been claimed as a source of annoyance, nausea, sleep loss and anxiety, among many other symptoms. Popular media continues to sell its threatening mystique, despite the existence of a multitude of experiments that have failed to show any harm at these low frequencies.

Recently, this stigma has impeded the development of infrasound-emitting wind turbines—a source of renewable energy. Thousands of anti wind-farm protest groups cite reports of detrimental effects of infrasonic noise as their primary weapon against the development of wind-energy. How did infrasound become stigmatized in the first place, and how do these associations continue to thrive?

Sensationalistic reports on the dangers of low-frequency sound originate from the unscientific research of the Russian-born French scientist Vladimir Gavreau in the 1960s. Gavreau used a precarious, let’s-try-it-and-see-what-happens approach to investigate human responses to sound, and it’s unclear whether or not he even was able to study the low-frequency sounds he claimed to. “Gavreau had no device to measure infrasound,” says Jörg Mühlhans, a psychoacoustic researcher at the University of Vienna who has written about the myths surrounding infrasound. “I have no idea whatsoever where he got the numbers for sound pressure levels from, when he could not even measure infrasound at all.”

While Gavreau’s research did indeed show some of the harmful effects of sound, what accounts of his research have overlooked is the difference between volume, which is perceived as loudness, and frequency, which relates to our perception of pitch. The notion that infrasonic frequencies are inaudible is actually a myth, because sounds within this range can be heard if presented at high enough volumes. Based on the numbers in his publications, Gavreau’s exploits involved dangerously high volumes, causing the reported “infrasonic” frequencies to be incredibly loud—levels that would be considered outrageously unethical by today’s standards. They were very likely to have been harmful, regardless of frequency.

“Everyone is surrounded by infrasound every day. It’s emitted by … the surf, storms, wind itself, our own heartbeat and respiration.”

    Gavreau was effective at aggrandizing his findings regarding such brutally loud noise. For example, he claimed that infrasound is “certainly one of the many causes of allergies, nervous breakdowns and other ‘unpleasant phenomena of modern life.’” He warned that it could lead to “exceedingly unpleasant new weapons.”

Only days after his 1968 publication titled “Infrasound,” a headline in the German newspaper Die Zeit appeared: “New Weapon: Infrasound?” alluding to the development of French infrasonic weaponry. Similar headlines included “Sound Ray developed as a Killer—French Working on War Machine” in the Miami Herald and “Sound as a Weapon of War” in London’s Observer. These false reports were even perpetuated by famed artists such as David Bowie and William Burroughs. Most amusing are descriptions of the famous “brown note”—a frequency said to cause instant defecation. Despite all these reports, such weaponry was never developed, because of the impracticality of creating viable, high-volume “noise guns” of such a deadly character.

Since these early reports, infrasound has been blamed as a source of everything from gag sensations, mental disturbances, and automobile accidents to absenteeism of school children and brain tumors. The case of the British lecturer Vic Tandy is particularly fascinating. In the 1980s, he apparently felt an eerie, dreadful presence at a distinct location in a medical manufacturing laboratory, while witnessing a grey paranormal entity in his periphery. After investigating, he concluded that it was infrasound from a nearby building fan causing both his anxiety and eyeball vibration that somehow resulted in the sighting. Although completely misguided, these conclusions came to be published in the Journal of Psychical Research and have been regarded by enthusiasts as a clever explanation for hauntings.

Apart from such diverting facets, in the ’90s, the discovery that wind turbines emit weak levels of infrasound soon stirred up protests. The growing list of symptoms reportedly caused by infrasound arguably culminated in the 2009 publication Wind Turbine Syndrome: A Report On a Natural Experiment, by Nina Pierpont. Her list includes: panic, sleep disturbance, headache, tinnitus, dizziness, nausea, and visual blurring. This list has since become central to a growing anti-wind community, but has not been recognized by any formal international classification. Today there are more than 2,200 anti-wind groups globally.

Yet infrasound from wind turbines is no different than infrasound caused by other harmless, common sources. “Everyone is surrounded by infrasound every day. It’s emitted by natural sources like the surf, storms, wind itself, our own heartbeat and respiration. We also are exposed to it in cars, from ceiling fans, motors, and urban noise,” says Simon Chapman, a professor emeritus at the University of Sydney. “If wind turbines were harmful to nearby residents, entire cities and small nations would be stricken across much of Europe, where we see the highest density. Copenhagen is surrounded by turbines but my Danish colleagues are not seeing queues of sick people.”

I emailed Pierpont to ask about her position, in light of the scientific evidence against it. She offered a new take on how wind turbines cause harm, seemingly different from the attribution to infrasound heavily implied in her book: “Wind turbines produce rhythmic, repeated air-pressure pulses that noise analyzers characterize as infrasound … but it isn’t,” she wrote. Her current belief is that the the negative effects are caused by  “repetitive stimulus the body is interpreting as seasickness.”

She elaborated: “I called this simply ‘infrasound’ in my 2009 book because the specific qualities of the wind turbine infrasound/low frequency ‘acoustic emissions’ had not at that point been defined.  My calling it ‘infrasound’ got me into hot water with certain acousticians, though I was attempting to sidestep the issue of exactly what the acoustic emission was and focus on the associated symptoms.”

What is certain is that prolonged exposure to unwanted noise at any level can be a source of great stress, and thus be very harmful despite a lack of any direct physical symptom. If people who live near turbines are continually told about wind-turbine syndrome, harmless infrasound can easily become very problematic. Geoff Levanthall, a senior U.K. acoustician, provided me with an example: “The proportion of sleep disturbance, which people attribute to wind turbines, is not very different from the proportion of sleep disturbance reported in general—about 30 percent. So a lot of people wake up during the night, and if they happen to live near a turbine, they say it was the turbine that woke them up.”

The situation resembles anxiety-inducing reports of the headaches, fatigue, stress, sleep disturbances, and even cancer misattributed to cell phones and other devices—computer screens, microwave ovens, power lines—when they were new. In a manner similar to infrasound, the fear stemmed from exposure to another invisible, inaudible phenomenon: electromagnetic fields. But extensive research has shown no harmful effects from exposure to low-levels.

Similarly, it might be only matter of time before wind turbines are widely considered a safe, viable clean-energy alternative to fossil fuels. “Right now there is no evidence of adverse effects other than through stress,” Leventhall says. “People’s concerns and their feelings are real. It’s how their feelings have arisen which are phony.”【全文完】