Infrasound: The Noise That Travels Further Than Any Other On Earth

So what’s the truth?

What is infrasound?

With its prefix being Latin for “below”, infrasound is exactly what it says: sound with a frequency below the normal limit of human hearing. In other words: real, real low noises.

The lower limit on what humans can hear, at least without workarounds like increasing the sound pressure, is about 20 Hertz – that is, a noise made by 20 vibrations per second. To give you an idea of just how low that is: the deepest famous bass-singer Barry White ever reached on record was an F#1, which has a frequency of about 46.25 Hz. 30 Hz sounds like this:

And 20 Hz, if you can make it out, is this:

Because these noises are below the range of human hearing, it’s hard to realize how many of them are all around us. But plenty of things are producing these ultra-low noises every day: wind turbines, waterfalls, and diesel engines all spread infrasound, as do romantic mainstays like lightning, the aurorae (really!), and the so-called “voice of the sea” – it’s a real thing, look it up.

There are even musical instruments that can hit these infrasonic notes, which is arguably kind of pointless given the purpose of a musical instrument – things like the amusingly huge octobass or hyperbass flute.

And of course, there are animals that can make these low noises – and hear them, too. Hippos, rhinos, alligators, and a bunch of other critters use infrasound to communicate over vast distances – as does one human guy named Tim Storms, apparently. Whales, famously, can project their infrasonic songs over thousands of kilometers, and elephants not only use ultrasound for communication, but also to hunt down super distant thunderstorms during times of drought.

It’s all very impressive – and it’s made possible thanks to one unique property of infrasonic frequencies: their durability.

The limits of infrasound

Your voice probably has a frequency of between 80 and 250 Hz – somewhere in the lower two-thirds of that range for dudes, and the upper two-thirds for ladies. It’s also, no offence, not that powerful: under the best possible conditions, using communication techniques specifically designed to help it carry, you can probably only be heard for a few kilometers or less.

Whales, on the other hand, boom out noises at a super-low 14 Hz – and as a result, they can be heard by their peers thousands of kilometers away. Volcanic eruptions can bottom out at 0.001 Hz, and the distances they can travel would be unbelievable if they weren’t supported by physical evidence. The 1883 eruption of Krakatoa, for example, “was the first infrasound measurement ever made,” François Coulouvrat, a physicist specialising in acoustics at the Jean le Rond d’Alembert Institute, told CNRS News in 2024, and was picked up by weather stations in London, more than 10,000 kilometers (6,200 miles) away.

“In London the wave was actually recorded twice,” Coulouvrat pointed out, “which means it travelled around the Earth at least two times.”

So, what gives infrasound its extreme long-distance durability? It’s nothing mysterious: low-frequency sounds have long wavelengths, meaning it takes more physical space to complete one vibration. That in turn means the vibrations are absorbed less by the surrounding environment, so they survive for longer.

“Higher frequencies are absorbed more rapidly in the air. This effect reduces as the frequency reduces,” infrasound expert Geoffrey Leventhall told the Michigan Land Use Institute in 2011. “Hence, infrasound travels further, but does weaken as it spreads out, just like any other wave.”

There’s an even weirder flipside to this long-distance spread, too: rather than being too far away, sometimes it’s possible to be too close to the source of an infrasound to actually hear it.

“During the First World War, the general staff of the French army called on scientists to help locate the enormous German batteries by calculating the direction of their fire, its time of arrival, etc.,” Coulouvrat explained. “That led to an odd discovery, namely that the shots could be heard near the batteries, not at all a few dozen kilometers away, and then once again moving further away.” 

“The din of war could be heard all the way on English shores, without the inhabitants understanding where these muffled sounds were coming from.”

Reactions to infrasonic (or: can a noise make you poop your pants?)

Evidently, infrasound has some intriguing properties. Some are useful; some less so; some are interesting, and others just plain perplexing. But there’s something else you may have heard about these ultra-low noises – so let’s do it. Let’s answer the question that, statistically speaking, at least some of you have been waiting for: can infrasound make you poop your pants?

There are two answers to this, and the first one is definitely “no”. The idea behind this claim – that certain infrasound notes can, upon hearing them, make your body suddenly and uncontrollably evacuate its bowels, regardless of your opinion on the matter – probably goes back to 1974, when a satirical article in New Scientist told a story of a “lost” Victorian instrument called the Collosophone. 

“As soon as the first notes crashed out, the audience showed signs of discomfort, which gave rise to a panic before a verse of the Anthem was complete,” the article related. “Moreover, the evident mass psychological disturbance was accompanied by unpleasant physiological symptoms: pain, dieresis, and diarrhea.”

Of course, no such event or instrument ever existed – and similar stories, such as those of the Republic XF-84H aircraft making bystanders crap their pants with its ultra-low, ultra-loud emissions, are equally unfounded. Overall, the evidence for the existence of a “brown note” is… well, it’s nonexistent. Sorry, acoustic pranksters: it doesn’t exist.

But there’s another way you can potentially use infrasound to humiliate your enemies’ bladders – you can use it to scare them silly. 

“I was sweating but cold, and the feeling of depression was noticeable,” Vic Tandy, an acoustic engineer and professor of information technology at Coventry University, told the Birmingham Post back in the early 1980s, after an intensely scary experience in an industrial laboratory.

“But there was also something else,” he said. “It was as though something was in the room with me.”

In the edge of his vision, he saw a gray shape. When he turned to look at the apparition, it disappeared. He felt, in his own words, terrified. What was going on?

The culprit, it turned out, wasn’t a ghost but a machine – specifically, a fan in the lab’s newly installed extraction system. The vibrations created by this movement were creating a standing wave with a frequency of about 19 Hz – too low for humans to hear, but apparently not so low that the workers couldn’t sense its presence at all.

Why precisely infrasound can have this effect – to make a person feel or even see a “haunting” – isn’t clear. It doesn’t seem to affect everybody equally, and modern parapsychologists don’t think it can explain the phenomenon of ghost sightings or hauntings on its own. But there’s definitely something to it – otherwise horror movie directors wouldn’t be using it to add extra freak-out triggers to their audiences.

So, next time you feel the hairs on the back of your neck stand on end, or a movie or piece of music hits just a little more strongly or strangely than it ought to – just remember. It’s not a ghost. It’s probably just a nearby elephant, looking for water.