[Note: This post has been edited slightly since it was first published, to clarify the difference between sound waves and radio waves.]
Everything new under the sun begins as an anomaly; but not everything thought to be new is genuinely new. Everything new and anomalous, if studied in the right way, can be explained; but it may take years of creative trial and error before we know what that “right way” is.
Those might be the twin mottos of the research field known as anomalistics — a field I’ve been interested in, without necessarily knowing it, since I read J. Allen Hynek’s book The UFO Experience at about age twelve. Hynek was the astronomer and scientific skeptic appointed to consult the U. S. Air Force on their Project Blue Book, started in 1952 to scientifically analyze UFO-related data and determine whether they indicated any threat to U. S. national security. Over the course of a few decades, Hynek came to believe in the reality of something he called the “UFO experience,” while never quite accepting the main explanations of that experience ascribed to it by the majority of its experiencers. (Briefly, the two predominant explanations are known as “ETI,” or the Extraterrestrial Intelligence explanation, and “EDI,” or the Extradimensional Intelligence explanation.)
The anomaly I’ve become particularly interested in recently is one known by some as “the Hum,” or “the Global Hum,” and it is one that I believe is somewhere on the trajectory of going from anomalous to explained. It’s also one that I believe has implications for how we think of the Anthropocene.
The Hum refers to a low-frequency humming sound reported by many people around the world. According to some accounts, it is global, though concentrated in particular places more than others. According to others, it is local, imagined, or just a loose and overgeneralized name for a wide variety of possible phenomena.
I’ve gotten particularly interested in The Hum because I’ve begun to notice it in various locations in and around Greensboro, Vermont, where I’ve just spent several weeks this summer. The Greensboro Hum — which I am the only person I know who has heard regularly — is an intermittent, foghorn-like drone at a frequency of about 60 Hz (cycles per second), which sounds like a low “B-natural” tone (slightly flattened) and which happens to be roughly the frequency of AC electrical currents in North America. The latter fact lends credibility to the hypothesis that this particular hum is related to some form of electrical current.
But it’s non-directional, which means that it seems to come “from everywhere.” I hear it in various places, indoors and outdoors, and even with my ear plugged by a finger. (It seems slightly louder in my left ear.) And it is intermittent: generally most audible in the late evening, at night, and especially in the early morning, and turning “on” for periods ranging from less than a second to more than a minute, but usually for a few seconds at a time. When it is “on” and I listen closely, I can hear an oscillation or pulsation that appears to be regular and at a frequency of 4-5 cycles per second (with a little “skip” around the 4th cycle).
This hum that I hear can also be modified or “played” to some extent by moving around, though this might simply indicate that it is combining with other, more immediate environmental sounds. Specifically, I can find places indoors where I can make it sound continuous, constant, and “wobbly,” with an audible pulse like one hears in a rumbling diesel engine (which is exactly how others often describe the hum). But this variability may well depend on how the “main” hum frequency combines with others generated by electrical appliances, such as fans, refrigerators, and the like, all of which appear to be able to shield it or cancel it out.
So am I going crazy? Apparently, no. Or not unless many people around the world are as well.
But the hum is selective. Data so far suggests that between 2 and 11 percent of people can hear it (where it exists to be heard), and that people in the 45-65 age range are more susceptible to it. (I’m 52.) But it has been reported and even studied in a variety of places going back to the 1950s, with particularly notable occurrences and/or studies in Bristol, England; Taos, New Mexico; Kokomo, Indiana; Auckland, New Zealand; and Windsor, Ontario — which doesn’t, of course, mean that these are all the same “hum.”
Numerous hypotheses have been proposed to account for the hum, including tinnitus or other kinds of “otoacoustic” emissions (which are generated internally by specific people’s hearing systems); cellular telephone transmissions; mechanical or industrial equipment of one kind or another; geophysical sources such as ocean waves, infragravity waves, or seismic processes; and a variety of government or military programs utilizing electromagnetic transmission signals, including LORAN, HAARP, and TACAMO (military communication signals used by the U. S. Navy).
A few researchers have attempted to develop combination hypotheses, according to which VLF (very low frequency) or ELF (extremely low frequency) radio waves are generated by specific phenomena or devices and compounded by particular conditions, triggering sounds that are audible only to a certain, low frequency-sensitive portion of the human population. By their nature, VLF radio waves travel very large distances and, if heard as sound, would seem to come “from everywhere.” If VLF radio waves traverse the planet more and more, then they are likely also to combine in unusual ways — which would suggest that the Hum is increasing.
Among the better scholarly articles on the phenomenon are David Deming’s 2004 article “The Hum: An Anomalous Sound Heard Around the World” (pdf warning), published in the Journal of Scientific Exploration, an interdisciplinary and peer-reviewed anomalistics journal. A recent popular article — which despite its alarmist headline is a good introduction to the topic — is Jared Keller’s Mic.com article “A Mysterious Sound is Driving People Insane — And Nobody Knows What’s Causing It.”
Perhaps the best, readily-available source of (anecdotal) documentation for the hum is the World Hum Database and Mapping Project. The project is run by hum researcher Glen MacPherson, who provides a number of possible explanations, including the following brief statement outlining his own preferred hypothesis for the “classic Hum,” as distinct from others that may be heard in particular places:
“I suspect that the Hum is a biological reaction to the multimode propagation and subsequent interference of VLF electromagnetic energy, compounded in some cases by existing sources of otherwise inaudible low frequency sound and infrasound. It is an activation of the auditory system detectable by a small proportion (less than 5 percent) of the population who are acutely sensitive to the presence of low frequency sounds or who have specific anatomical conditions. Increasing numbers of increasingly powerful VLF transmitters, via ground wave, skywave, and magnetic conjugate propagation modes, create ground interference and standing waves that create locations with intense levels of VLF energy. The odd behaviour of the Hum is caused by diurnal, seasonal, and geomagnetic disturbances affecting the ionosphere.”
“There is now a workable theory to explain how pulsed (oscillating) radio waves at lower frequencies can activate human nerve cells. For more than 50 years, increasing numbers of powerful VLF transmitters (mobile, stationary, and airborne), have been in operation. By line of sight, ground wave, sky wave, antipodal focusing, and geomagnetic coupling, the surface of planet Earth is riddled with zones of oscillating and high intensity VLF electromagnetic (EM) radiation.
“A small proportion of people – I now estimate no more than four percent of the adult population – have auditory systems that are sensitive to lower frequencies and the type of biological activation described in the above paper. They may be able to detect the Hum in many places on Earth solely by interaction with VLF, while there may be another group of people who need some extant sub-audible low frequency sound or infrasound at certain frequencies in order to create sufficient auditory activation that would be interpreted as sound. Also, because the majority of Hum hearers are in the 40s or older, it is possible that certain age-related anatomical changes may initiate Hum hearing.
“Sources of industrial infrasound, such as mining, hydro-electric projects, windmills, high pressure gas pipelines, and massive construction projects may or may not be prerequisite or aggravating factors in some settings. When there is strong but sub-audible infrasound such as from a large industrial site, it may take little VLF exposure in order to activate the auditory system. High levels of ambient noise during the day from traffic, industry, mechanical devices, and other people, often mask the Hum and explain why the Hum is stronger at night when society has quieted down somewhat, and why the Hum can become very loud in sound-reduced rooms.
“If the Hum is rooted in VLF energy, it is therefore affected by the behaviour of the Earth’s magnetic field and by the height and layers of the ionosphere, solar activity, the time of day, and the season. The Hum also is rooted in the particular radio frequencies that governments use for communication. Therefore, when a powerful VLF transmitter suddenly stops broadcasting or changes frequency, this will cause a simultaneous change in the Hum at multiple locations across the planet. During a big solar storm, anything could happen. In fact it’s been shown the correlation between solar activity and posting activity on some Hum support forums is very high. The Hum can also slowly drift over an area as do the entry and exit points for geomagnetic conjugate magnetic field lines.”
So what is the upshot of all this planetary humming for environmental thought and scholarship? The global hum (or hums), if it is (/they are) a new phenomenon — and evidence suggests it has increased over the last 50 years or so — is a new element of the global soundscape. Even if only a small proportion of the human population hears or is affected by it — and hearing something is not necessarily equivalent to being affected by it — there is little reason to believe that at least some other organisms won’t hear or perceive it as well. Those, like elephants, whales, rhinos, hippopotamuses, pigeons, and many others known to make use of infrasounds — sounds lower than the range of typical human hearing — would be particularly vulnerable to being affected by VLF radio waves and their effects.
It’s not clear to me why, as MacPherson puts it, “industrial infrasound, such as mining, hydro-electric projects, windmills, high pressure gas pipelines, and massive construction projects” would be “prerequisite or aggravating factors” in hearing the Hum. But if this is the case, then all such factors have been increasing in the last 150 years or so. And even if they are not “prerequisite or aggravating factors,” the increase in artificially generated VLF radio waves around the planet — a fact that has hardly been studied — would suggest that human activities are having effects we can hardly comprehend on species around the world.
In other words, welcome to the Anthropocene, generator of anomalies, novelties, and challenge. Have a good visit, and good luck with it.
Some further reading
- World hum Database & Mapping Project: http://hummap.wordpress.com/
- http://sandaura.wordpress.com/ – A blog with the catchy (!) subtitle, “The hum heard around the world is explained and we are all being lied to”