David Hendy can be lying in bed, driving on the highway, or flying in a commercial airplane, when suddenly his ears perk up. Does the heating boiler always rattle so violently? Is that the car engine making a horrible clanging noise? Why are thuds and creaks enveloping the cabin?
His thoughts start racing.
"Oh my word, it's going to explode," Hendy thinks. "The car is going to break down completely. I'm going to fall out of the sky!"
Sound familiar? There are a lot of noises that do us in like this. They can be inorganic and deliberate, such as the theme from Jaws, or organic and random like a blood-curdling scream or a piece of malfunctioning machinery. Hearing them makes us uneasy.
"I think that's something that gets to most of us in different ways," says Hendy, a media historian at the University of Sussex and author of Noise: A Human History. And it's when a noise is not just unfamiliar but vague, he adds, that we tend to then amplify any anxiety and dread we've attached to it. "We imbue into it our worst fears," Hendy tells me.
The heater is about to burst. The engine is melting. The plane is rattling apart. Or so we think.
It's not entirely clear why we do this. Something happens in our heads when we hear things that unsettle or frighten us. But exactly how does it all kick in, and how might this complex, primal auditory fear circuit be evolving in an age awash in digital noise?
It all starts with the connection between the brain and the ear. The ear acts as a "mechanoelectric transducer," Dr. Carmen Brewer, a research audiologist with the National Institutes of Health's National Institute on Deafness and Other Communication Disorders, told me over email. In this sense, the ear detects mechanical activity (sound waves) and generates electrical signals based on that activity (vibrations). The ear then shoots those signals to the brain via the auditory nerve, at which point the brain then converts those signals into sounds.
In other words, hearing. It's one of our hardwired abilities as humans to detect sound waves. But it's more than that. Hearing, Brewer explained, can also refer to auditory perception and assigning meaning to sound. We learn to make associations based on what we hear.
"You hear speech, you understand what is being said," she said. "You hear a dog bark, you know the animal. You hear a phone ringing, you look for it because you know the sound, and if you don't remember where you put the phone, you use auditory cues to figure out the location."
Those aren't necessarily creepy noises though. At least, not like this:
Audio by William Aubé. Used with permission.
Or like this:
Audio by William Aubé. Used with permission.
Bad vibes all around, right? That's precisely what William Aubé was going for. Aubé is a neuropsychologist at the University of Montreal interested in how our brains respond to the emotional power of music, and he created these and other novel musical excerpts and non-linguistic vocalizations as part of a study exploring fear across the senses.
We know how hearing works. Our ears are programmed to lock onto sound waves, or mechanical vibrations, and pulse them to our brains. (Brewer told me most cases of deafness, the inability to detect sound, result from damage to the cochlea, the tiny inner-ear structure that converts sound to nerve impulses sent to the brain.) But what is it about hearing certain noises that then makes us fearful? And are those regions of the brain often associated with the processing of "biologically relevant" emotional expression—a blood-curdling scream, say—likewise activated by emotional music, and by extension, similar inorganic or deliberate noise?
It's a question that lies at the heart of a study led by Aubé that was published last year in the journal Social Cognitive and Affective Neuroscience. What he and his colleagues found offers key insight on how vital fear is in emotional communication in humans, and just how powerful noise is in triggering raw anxiety, fear, even the pangs of post-traumatic stress.
The study used functional magnetic resonance imaging, or fMRI, to measure brain activity in 47 participants who were subjected to 180 semi-random emotional cues across three domains of stimuli: grayscale pictures of facial expressions (60), non-linguistic vocalizations (60), and short, novel musical excerpts (60). Each of those three domains had four specific emotional categories: happy, sad, neutral, and fear.
The subjects, all of whom had no history of hearing problems, took it all in wearing MRI-compatible goggles and headphones. The research team then directly compared how the participants responded to those four basic emotions as expressed through a range of faces, vocalizations (laughter, cries, screams, coughs, and yawns), and instrumental clips, including piano and violin.
Noise is a sound out of place.
The fear was strong in all the participants in all situations. The researchers observed "significant" amygdala and anterior insula activation in subjects' responses to fearful expression across the three top-level domains. There are strong links between fear and the amygdala, an almond-shaped structure in the brain's temporal lobe, and also ties between emotion and the anterior insula, a deep-seated portion of the cerebral cortex. It wasn't exactly Earth-shattering to see those two areas of study participants' brains light up.
"Fearful faces, vocalizations and musical excerpts elicited significantly larger activity in this region when compared with their neutral counterparts," the researchers wrote at the time. "This is consistent with the established role of the amygdala in the processing of threat-related stimuli, both in the visual and auditory modalities."
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The researchers did note a correlation between subject-specific amygdala responses to fearful music and vocalizations. It's a curious observation insofar as Aubé and his team did not observe a similar phenomenon with facial expressions. The amygdala response correlation between fearful music and vocalization, the researchers wrote, supports the idea that music and voices potentially have a shared emotional neural circuitry in humans.
The role the amygdala plays in our making sense of creepy noise, it would seem, is not confined to intrinsic or "biologically relevant stimuli." It's not confined to the organic and random, to blood-curdling screams and malfunctioning machines. It too lights up when we hear inorganic and deliberate noise like brooding piano or the Jaws theme.
And the dividing line, between organic-random and inorganic-deliberate noise, is blurring.
The operative word in all of this is "noise," which is not the same thing as "sound." Distinguishing the two is crucial to our understanding of not only why hearing certain things gives us the creeps, but how our processing of fear across the senses might be changing in a soundscape awash in digital noise.
A good way of thinking about it is that all noise is sound, but not all sound is noise. Noise is a sound out of place. It's something unfamiliar, something that does not compute, according to Hendy, which can unsettle us.
Imagine an insect buzzes your ear, or a small mammal scurries near your feet. If you're hiking in a forest, no big deal. It's a perfectly normal part of the soundscape.
"That's not at all creepy," Hendy says.
But say you're lying down for the night in your bedroom. It's pitch black and an insect buzzes your ear, or a small mammal scurries across the wood floor. That is not normal. It's the right sound in the wrong place and at the wrong time. It's a spatial or chronological anomaly (a mosquito or squirrel in your room) that breaks the expected background pattern (silence indoors). It's what's sometimes called "nonlinear chaotic noise". It's something that stands out. It shouldn't be there. It's unexpected.
"That is very creepy," Hendy says.
That's because our brains, in his words, are "anomaly detection machines." They're fine-tuned for picking out things that stand out. Linked with our ears, we've got an impeccable early warning system.
"If these become familiar, the soundtracks of our lives, then all sorts of other things become disturbing and unfamiliar."
Aubé, the neuropsychologist, uses a slightly different analogy for the brain though it plays to the same idea, that we efficiently take in information and then develop expectations to predict what will happen next. He likes to think of the brain as a "predicting machine" that helps us adapt to our environment. Sometimes that means listening closely to our fears.
"It might be more important to stay alive if you hear something bad in your environment, than staying happy all the time," Aubé tells me.
Evolution is slow. "Our brains won't change tomorrow," Aubé admits. Though he has no doubt that in the changing age, "with electronic sound and digital noise, the brain can necessarily be cautious. On alert mode."
Even if our brains can adapt to changing environments despite being hardwired, the way our brains function is practically unchanging, in many respects, in our lifetimes. It's just that the nature of that environment, of our environment, is changing.
Our sense of the familiar and of what provides us reassurance and grounding in time and space varies. Our sense of what becomes strange, of what is unsettling by virtue of its out-of-placeness, varies too. Today's soundscape is still punctuated by classic bumps in the night and other vague and horrible noises, the sort that get your thoughts racing on a long flight. But it's also saturated in digital noise, an electronic din of pings, whooshes, whirring. Bleeping and buzzing phones.
"If these become familiar, the soundtracks of our lives, then all sorts of other things become disturbing and unfamiliar," Hendy says. Things that were fixtures of the soundscape, say, 200 years ago, suddenly have our ears perking up. Birds chirping. Church bells. Or the silence plaguing overly-soundproofed offices and those whose reliance on technology is driving them away from routine face-to-face interactions, with only the echo of intermittent chatter and cold, low-level pings ringing in their ears.
Sheer loudness can make an already terrifying noise more terrific and disorienting. This is why noise torture hurts so bad. It disconnects the brain from normal, everyday acoustics that help us navigate the world. It's about draining what can be sensed. Loud noise erases one's grasp of time, place, and self.
Hearing no noise can have the same chilling effect. Total silence, washing away the human touch, amplifies perhaps the scariest thing of all: being alone.
All in Your Head is a series that takes a scientific look at all things spooky and scary. Follow along here.