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Hey, smart people, Joe here.

When I put on these headphones, I have no idea what sounds I'm about to hear or how I'm gonna react.

(nails scratching on chalk board) We can make that one stop anytime.

No, no.

(baby crying) That does nothing to me.

I'm immune.

(squishy chewing) It's like they're in my head.

I don't like that at all.

To many people, these are the most horrible sounds imaginable, and I want to figure out why.

(person vomiting) Not great.

But not the worst.

(mic feedback) Oh.

(styrofoam scraping) Uh-huh, no.

I can't listen to that.

(blowing raspberry) Not again.

I told you not again on that.

Some of these sounds were genuinely horrible to experience, but to me most were just kind of a annoying.

Yet, for some people, hearing sounds like these is genuinely, stomach-churningly, anxiety-inducingly awful, often to the point that it can disrupt their lives.

Certain words can also have this effect, like moist.

(pensive music) Moist.

For many of you, if you hear that in a sentence, you throw up a little in your mouth.

This is weird, right?

It's not like the sounds themselves can physically harm us.

Sounds don't carry icky germs that can threaten our health.

So what is it that makes some sounds so horrible?

God, that was terrible.

Let's never do that again, please.

(bright music) Hey guys, before we get back over to the cool science, I just wanna take a moment and say thank you to everyone who supports the show on Patreon, including these fine people here at our top tier and so many others.

There is a link down in the description.

You can learn more, support the show and help us make more videos.

And when researching this video, I was amazed to learn that there are a lot of people out there who really get bad reactions when they hear certain awful sounds.

But we do need to play some awful sounds to learn about awful sounds.

So here's what we're gonna do.

Right before a maybe gross sound happens, look for this little graphic in the corner.

That'll give you a second to maybe hit mute, turn on the captions, and we'll all enjoy this together.

I'm not some kind of monster.

I'm not trying to torture you.

I'm a nice guy.

Okay, let's get back over there.

So why do we cringe when we hear a balloon squeaking or someone chewing or rubbing two pieces of styrofoam together or saying the word moist?

The answer to this question lies at the intersection of human evolution and social psychology.

In 2007, sound scientist Trevor Cox set off on a dubious quest to identify the worst sounds in the world.

So he did what, in 2007, was a revolutionary way to run an experiment, he asked the internet.

But Cox figured that if he could get people to listen to awful sounds and rank them, he would've a big enough sample size to determine which sounds are the most hated.

So he set up the raddest website of all time.

I mean, it has flames, flash animations.

Perfection.

Hundreds of thousands of participants from around the world played 34 sounds ranging from a whoopy cushion (mimicking flatulence) to microphone feedback.

Then they ranked each one on a scale of whatever to totally revolting.

In the end, his experiment gathered over 487,000 responses, and there were some pretty clear winners: babies crying, (baby cries) followed by microphone feedback with vomiting being the number one worst sound in the world.

Later experiments have found similar results with sounds like silverware scraping on a plate taking the top spot.

Reminds me of a painful childhood memory.

- What're you going to do?

(chair shuffling) What're going to do?

- Whatever I have to to get some answers.

(metal and ceramic scraping) But what makes these specific sounds so awful?

Well, to figure that out, let's start with what sounds are and how we hear them.

(upbeat music) You know that one scene from "Jurassic Park"?

(ominous thud) That's pretty much how our ears work.

Let's slow the process down a bit.

When an object or voice vibrates, it pushes air particles together and pulls them apart creating pressure waves that travel to our ears as sound.

Those waves are collected by our outer ears and funneled down to our eardrums.

These membranes vibrate back and forth as the sound wave energy hits them just like a drum.

As our eardrums vibrate, they cause the smallest bones in the human body to lever back and forth like a seesaw, amplifying and transferring sound vibrations to these fluid-filled snail looking structures.

These are covered in super sensitive tiny hairs that translate sound vibrations into electrical signals that get interpreted by the sound-processing centers of your brain.

And then you run, obviously.

(animal roars) Of course, extremely loud sounds are registered by our brains as pain because these can physically damage hearing structures.

But sounds that our brains interpret as bad do have a few things in common.

The first is the sounds frequency.

Scrapy noises like nails on a chalkboard have a high-pitch frequency range of about 2,000 to 5,000 hertz.

You know what else also falls into that frequency range?

Human screaming.

(person screams) Some scientists think our sensitivity to this high-frequency range is because we've evolved to hear distress calls and screams.

(animal screeches) Like, if you hear this, (animal roars) you're gonna want to head the other way.

And why do you think sirens sound the way that they do?

(sirens wailing) You evolved to pay attention to those sounds.

So when a sound is high pitched and loud, it totally sets off alarm bells in our amygdala.

It's an ancient part of the brain that helps trigger our fight or flight response.

Your amygdala thinks that sounds in the 2,000 to 5,000 hertz range sound like things that can hurt you even if they aren't actually things that could hurt you.

So just in case, it fires up your fight or flight response anyway.

That's why when you hear this, (styrofoam scraping) you wanna do this.

(wall smashes) These kinds of sounds can even make us physically feel bad.

This is especially true for people who experience more extreme physical, psychological, and behavioral reactions to unpleasant sounds.

- I'm Dr. Jane Gregory.

I'm a clinical psychologist and I research misophonia.

Misophonia is a a decreased tolerance or an intense reaction to everyday kind of sounds that most people would find maybe mildly annoying or not notice at all.

- [Joe] Not to be confused with misophobia, the irrational fear of fermented Japanese soybean paste.

- It is a very personal topic to me.

So all throughout my childhood I was really strongly affected by a handful of sounds, and the big ones for me were chewing sounds, and embarrassed to admit that I would grab food out of people's hands because I was so angry and didn't know what to do with those feelings when I was a kid, clocks ticking, pens clicking, that sort of thing.

When I discovered that misophonia was a real thing, it had a name, and I was not the only one who reacted this way, I was naturally drawn to wanting to research it, wanting to find out ways to help other people with this problem.

- [Joe] Based on research and surveys, estimates for how many people experience misophonia range from 1 in 30 up to as high as 1 in 6 people.

- A lot of the sounds that people who have misophonia are affected by are sounds that most people would find annoying.

But there's a really big difference between being annoyed by that sound, finding it irritating or disgusting and having a misophonia reaction.

And the misophonia reaction is more of, like a fight or flight kind of response.

People feel rage, they feel panic, they feel trapped and helpless if they can't get away from the sounds, they worry that they might explode or have a panic attack or do something that they regret.

- If you have misophonia and hear a triggering sound like someone smacking a piece of gum, your blood pressure and heart rate might spike involuntarily.

You may even start sweating and feel chills run up and down your spine.

And for some people, trigger sounds can migraines and panic attacks.

Now, unfortunately for folks with misophonia, some trigger sounds can be really common things like the rustle of a potato chip bag or someone chewing.

While these noises might not bother most people, for someone with misophonia, they can be really disruptive.

- There's another part of misophonia, which is not being able to go places that you would like to be able to go, not doing things that you want to do because you don't want to encounter the sounds that might be there.

It causes really significant distress.

It affects their life, it stops 'em from doing what they want to do.

It affects their relationships, it affects their work, their study, so there's a really big difference between not liking sounds and then being affected by sounds and then really having your whole life impacted by misophonia.

- [Joe] Even strangers still is how much these triggering sounds can depend on context.

(celery crunching) Some people with misophonia will be deeply affected by hearing the sound of someone chewing celery, until they find out the sound they're hearing is actually a panda chewing on bamboo.

The context can trigger a completely different reaction.

- I met somebody who said they were very specifically triggered by the sound of hot water pouring, but not cold water pouring.

And so making a cup of tea, and for a British person being affected by the sound of making a cup of tea is a real problem.

(chuckles) We know that there's something going on in the body, and similarly, we know that there's something different going on in the brain when people hear these sounds as well.

There's these connections that are happening in the brain specifically in response to trigger sounds that are really different from when they're hearing neutral or unpleasant sounds.

- These intense reactions suggest that when we hear certain horrible sounds, our brains want to protect us from something that wants to hurt us.

That's because in addition to our ancient, almost hardwired fight or flight responses, humans have also evolved disgust.

Disgust is an unconscious, psychological and physical response that we have that prompts us to avoid or move away from stuff like bodily fluids or dirty environments, even certain foods.

Basically our disgust response kicks in to help us avoid things that could make us sick.

It's why we instinctively wrinkle our nose when we see someone leave the restroom without washing their hands, or why scooping the litter box can make you dry heave no matter how cute your cat is.

(cat meows) So one potential reason the sound of barfing is so disgusting is because barfing is also a pretty universal sign of disease, so our brain, specifically the amygdala again, triggers the physical response of disgust, so we don't accidentally punch our on ticket on the Upchuck Express.

But while some of our disgust responses have been deeply programmed by millennia of evolution, there are other things that we've been taught are gross.

This is what psychologists call social conditioning.

(person slurping) Like if I slurp my noodles, my noodles can't physically harm you.

And yet you might have the same visceral reaction as you would to someone, say, hawking up a loogie in the middle of the street, that is, if you're American.

If you're in Japan, on the other hand, soup slurping is encouraged as a sign of respect for the chef.

This is an example of how sometimes we feel disgusted because we've learned that that's the right way to react.

We want to fit into our social groups, and disgust can reinforce the values of our particular culture.

This subjective aspect of interpreting sound also explains why something that sounds awful to one person may not be so bad to another.

Like a baby crying might drive someone else up a wall, but I have kids, okay?

I'm basically immune to the sound now.

It's my superpower.

But if you sit next to me and tap your pen on the desk incessantly without stopping, I'll shove it in your ear, metaphorically speaking, of course, but also for real.

Finally, this innate disgust response can also explain why we hate certain words.

You weren't going to get outta this video without hearing the word moist again, okay, or dank or phlegm or moist.

Oops, did it again.

♪ Yeah, yeah, yeah, yeah, yeah ♪ Turns out many of the words we hate are pretty much the linguistic equivalent of barf sounds.

They evoke the images and sometimes memories of bodily excretions and secretions that come with illness.

Ew.

If it was the actual physical sounds of words like moist that bothered us, then we'd also be disgusted by words like hoist or joist.

But unless you have some vendetta against cranes or carpentry, that's not really a thing.

So moist, well, it makes you remember that sensation like when your shirt sticks to your sweaty back in the summer.

You know when else you sweat a lot?

When you're dying of the plague.

Or take phlegm, it makes you think of that thick grossness in your throat when you're sick.

Even dank evokes memories of maybe your middle school locker room post-PE class.

And none of us wanna go back to the smells or emotions of that time in our lives.

So while the memes may sometimes be dank, the word's pretty icky.

Thinking about awful sounds might feel bad sometimes.

This can actually be a really good thing.

When we understand the why and how behind horrible sounds, we can make society more accessible for people who have lower sound tolerance.

- If you think about the fact that this is affecting maybe 17 or 18%, that's nearly one in five people are affected by this.

If more people knew about misophonia and knew the effect that it has on people when they hear these sounds, then that could make a huge difference for how people make noise in public spaces.

Just being aware that some people are internally suffering because of the sounds that other people are making and being more thoughtful about what you do in public spaces.

- Maybe that means making quieter air conditioners or setting quiet hours where no jackhammers or leaf blowers are allowed at eight o'clock in the morning when you're trying to sleep in on a Saturday.

Or maybe it means being more understanding when someone tells you that you're chewing too loud.

It's not you, it's evolution, and a little bit of mismanners.

So, so both.

There are actually multiple categories of worst sounds ever.

Some sounds are terrible because they set off our innate fight or flight responses, and other sounds are awful because of when or where we hear them, or our own past experiences.

And still other sounds are horrible because our culture or society has taught us they're bad.

So what's your least favorite sound?

Leave a comment and let me know.

And while you're at it, stay curious.

Moist.

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Ow.

The more I say these, it's really, they're just, I get it, okay.

I think I nailed it.

(producer chuckles)