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Join us on a fascinating journey as we uncover the remarkable way animals perceive the world around them.
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00:00Chances are, you have a dog wagging its precious tail around the house or sniffing at your feet.
00:06Ever marveled at how keen your dog's hearing is?
00:09I mean, it can hear you opening a bag of chips even if you're on a different floor in the
00:14house.
00:15Even with this amazing ability, most household dogs don't have the best hearing in the animal kingdom.
00:21Actually, they're not even in the top five.
00:24On that note, let's venture into the world of animal hearing and try to imagine what life sounds like for
00:31other creatures.
00:33Look, we humans are pretty great.
00:36We've got all kinds of talents, but when it comes to the Auditory Olympics, we're not even in the running.
00:41Put us next to a cat or a bat and our ears look kind of basic.
00:45Take elephants, for instance.
00:47They are big animals, and so are their ears.
00:50Their auditory organs are capable of capturing infrasound waves.
00:55Now, these are not your run-of-the-mill sound waves.
00:58They're low-frequency, rumbling whispers that we humans can't hear.
01:03This means elephants can pick up on things like rain clouds on the move.
01:07Not only that, but these massive mammals have a pretty clever way of communicating, too.
01:12They stomp the ground, creating vibrations barely noticeable to us.
01:17But to elephants, these vibrations are the equivalent of a long-distance phone call.
01:23The messages are received through their feet and ear bones, even when they're miles apart.
01:29Talk about having a good reception.
01:34Moving on to bats.
01:36They are the masters of night navigation, thanks to their use of echolocation.
01:42These animals emit high-frequency sounds, which bounce back after hitting objects.
01:47This echo helps bats create a mental map, allowing them to sway flawlessly in the dark.
01:54Just when we thought bats couldn't get any cooler, scientists discovered their hearing capabilities extend to their wings.
02:02Special hairs called Merkle hairs sense air movements, helping the bats detect upcoming objects.
02:08It's not the traditional hearing we're used to, but it's a fantastic adaptation to their environment.
02:17Dolphins, on the other hand, are masters of watery acoustics.
02:21For starters, you might think that being underwater would put a damper on hearing.
02:25But dolphins have turned this challenge into an advantage.
02:29They've got their own version of echolocation, emitting sonic pulses from their foreheads.
02:34These sounds bounce off objects and are picked up by the dolphin's jaw before being sent to the brain via
02:41highly developed auditory nerves.
02:43Their ears, though present, don't play a central role in hearing like ours do.
02:49Instead, dolphins have found innovative ways to listen, proving yet again how awesome animals are.
02:57Don't let their domestic status fool you.
02:59Your pet cats and dogs are auditory champs.
03:02Cats' ears are designed to catch high-frequency sounds from up to 160 feet away.
03:08Handy for catching mice, don't you think?
03:11Dogs, on the other hand, are pros at localizing sounds, thanks to the muscles around their ears.
03:18Ever seen your pooch perk up their ears when they hear something suspicious?
03:22That's their sharp hearing at work.
03:27Even the tiniest critters buzzing around us, like insects, can actually listen to the world.
03:34In fact, some insects have something akin to our human eardrums.
03:38It's a delicate little membrane, given the name tympani.
03:42Our eardrums jiggle with the sound waves.
03:45That shaking is then turned into a signal our brain would understand.
03:49Now, you've surely heard the nightly serenade of crickets or the rhythmic song of cicadas in the summer.
03:56These little symphony masters use exactly this kind of setup to listen to their world.
04:02That's not all, though.
04:04Some bugs take a different approach to eavesdropping on their surroundings.
04:08They've got these sensory cells right in the middle of their antennae.
04:12This structure is called the Johnston's organ.
04:15Take mosquitoes, for instance, or bees, or even fruit flies.
04:20They use their antennae, not just to feel their way around, but to listen in on the world, too.
04:26It gets even wilder.
04:28Hawk moths, some dusky, nocturnal creatures, have this unique organ nestled right in their mouths.
04:34It's like a superpower that lets them hear ultrasonic sounds.
04:39With this, they can dodge the dangerous dives of bats out on the hunt.
04:47When it comes to the ultimate hearing trophy, the animal kingdom has a completely unique winner.
04:53It's actually a moth.
04:55Not just any moth, though.
04:57It's the greater wax moth, discovered by the scientists based in Glasgow, Scotland.
05:02They've got some fascinating insights about these moths that make our ears want to stand up and listen.
05:10Just to give you some context, the greater wax moth does not stand out when it comes to its appearance.
05:16I mean, it's brown.
05:19As for its daily activities, it loves nibbling on honeycomb.
05:23Despite blending in seamlessly in the animal kingdom, it's got a serious set of ears.
05:29How good is its hearing, you ask?
05:32Well, it's been found that this tiny creature can pick up on sounds at frequencies up to 300 kilohertz.
05:39By comparison, our human ears can only detect sounds up to around 20 kilohertz.
05:45This already unimpressive ability drops to about 15 kilohertz as we grow older.
05:52I mean, not even dolphins can compete.
05:54They can only hear sounds up to about 160 kilohertz.
06:01You're probably wondering, why would a moth need such super hearing?
06:06Scientists explain that the reason behind this extraordinary hearing lies in a survival instinct.
06:12Predation, to be precise.
06:14Bats use high-frequency echolocation calls to find their tasty moth meals, amongst other insects.
06:21But these clever little moths have evolved to pick up frequencies even bats might not hit.
06:28Despite this reasoning, it was a bit of a mystery as to why these moths would even need to hear
06:33such high frequencies.
06:35During the research, specialists discovered that their recording at high-frequency ultrasound is tricky business.
06:42So there's a chance that bats might actually be capable of emitting calls at these super-high frequencies that the
06:48moths can hear.
06:50To uncover all this, scientists used a specially designed ultrasonic device.
06:55It emitted these crazy high frequencies, and they then looked at the moths' reactions using electrodes to measure their neural
07:03responses.
07:07The practical implications of this research could be far-reaching.
07:11Understanding the inner workings of the greater wax moth's ear could have a big impact on the world of technology.
07:17This knowledge could help researchers build super-tiny microphones, for example.
07:24We know that all sorts of critters, from the tiny creatures scuttling on the ground to the gigantic ones swimming
07:30in the ocean,
07:31can pick up on certain sound frequencies that our human ears just can't.
07:36However, scientists have made a fascinating discovery.
07:40They've shown, for the first time, that our ability to pick up on tiny differences in sound frequencies
07:46might just be superior to that of animals, thanks to our individual neurons.
07:53How did they prove this, you ask?
07:55Well, they took advantage of a unique technique that lets them record what single neurons are up to in the
08:01auditory cortex.
08:02That's the part of our brain that's a major player in processing sounds, when we're exposed to various noises.
08:10You see, most of what we know about the auditory cortex was unearthed from past research
08:16that studied how animals' neural activity reacts to sound.
08:20Those studies were super useful in giving us a peek into how sounds are processed in our auditory system.
08:26But they didn't really let us know what sets us humans apart in the way we perceive sounds.
08:34When scientists tested how we respond to made-up sounds,
08:37they found out that our neurons in the auditory cortex responded with a surprising level of accuracy to specific frequencies.
08:45They could even pick up differences as tiny as a quarter of a tone
08:49just by looking at the reactions of individual neurons.
08:54That's a level of detail that you wouldn't typically find in the auditory cortex of other mammals.
09:00The one exception might be bats, who use their hearing in pretty unique ways.
09:05But this could explain why we humans can distinguish between frequencies better than animals.
09:10It seems like the way our brains process sound frequencies has some special features to it.
09:17When they played more natural sounds like conversations, music, and everyday noise,
09:23the neurons showed complex activity patterns.
09:26These patterns couldn't be fully explained just by the neurons' frequency selectivity.
09:31Animal studies have shown similar phenomena,
09:34but it's the first time we've seen this in humans.
09:37Since the beginning of time, humans have shared the world with other species.
09:42Each one has a unique perception of what reality is like in terms of color, speed, and sound.
09:49Today, thanks to technology, we can more or less understand how our world sounds to animals.
09:55So how about we try living with their ears for a bit?
09:59Let's start with man's best friend, dogs.
10:03It is known that dogs experience time quite differently than our own.
10:07The best guess is that one human year equals seven dog years.
10:12But when you call out their names, what exactly do they hear?
10:17Dogs experience our world slower than humans.
10:20That works both for their perception of time, but also for sound.
10:24Let's say you're calling Skipper to go for a walk.
10:27You're speaking at a normal pace like you do every day.
10:31But to Skipper, he's hearing you in slow motion,
10:34as if you just pressed the 0.75 speed on your Spotify app.
10:39You've also probably heard that dogs have a wider hearing range than humans,
10:44and that they can hear sounds from a very great distance.
10:47And this is true.
10:50An average human being has a hearing range from 20 hertz to 20 kilohertz.
10:56We hear better when we are younger, and tend to hear less when we get older.
11:01Yep, this is actually scientific.
11:03But our dogs can hear up to 45 kilohertz, which is considerably more than us.
11:09Some dog breeds are known to be good hunters, and for that reason, they would need better hearing equipment.
11:15The thing is, dogs aren't as good as humans at distinguishing sounds.
11:19Humans easily know the difference between slow and go, while dogs, not so much.
11:26This is called frequency selectivity.
11:29The scientific explanation for this is that different parts of the cochlea answer to different frequencies.
11:35This is what a human ear looks like on the inside, and this is what a dog's ear looks like.
11:41The cochlea is this part right here that looks like the shell of a snail.
11:46It's made up of saltwater-like fluid.
11:49At the innermost center of this cochlea, there are tiny hairs that vibrate according to the frequency of sound we
11:55are receiving.
11:57Some hairs will only be activated by high-pitched sounds,
12:00while other hairs will be activated with lower notes.
12:05Dogs really prove to be humans' besties, as they also tend to lose their hearing with old age.
12:11You see, human hearing is at its prime when we're young.
12:16A study from the University of New South Wales says that a child can hear up to 24 kilohertz.
12:22When we're young, we can hear extremely high-pitched sounds, but this tends to decrease once we get older.
12:28The maximum hearing capacity of an older person can go as low as 8 kilohertz.
12:34I mean, this person probably can't hear the birds chirping, or even the beeping of their microwave.
12:40Both in dogs and humans, the loss of hearing has to do with the loss of the tiny hairs in
12:46the cochlea.
12:47And what about cats?
12:49Cats can hear higher frequencies than dogs.
12:52Their hearing can go a little beyond 60 kilohertz.
12:56This is especially important since they hunt small rodents that make almost imperceptible noises to our human ears.
13:04But with a cat's hearing device, it can pick up on a mouse hiding in a bush over 100 feet
13:09away.
13:09The funny thing is that while dogs experience reality in slower motion than humans do, cats actually experience life about
13:189% faster than we do.
13:21You've probably heard that sound can also be classified as either infrasound or ultrasound.
13:27Here's what we'll do.
13:28I'll give you an example of a sound, and you'll tell me if you think it's infrasound or ultrasound.
13:34Would you say the sound of tectonic plates moving around is infra or ultrasound?
13:39The correct answer is infrasound.
13:42This one is tricky.
13:44The movement of ants in an underground tunnel.
13:47Also, infrasound.
13:49Infrasounds are low-range frequencies.
13:52Anything ranging below 20 hertz, which means we can't hear them.
13:56But an elephant can.
13:58When you look at elephants, one of the first things you'll notice is their enormous ears.
14:04Well, everything is pretty gigantic, but the ears are impressive, especially in comparison to ours.
14:12Their ears allow them to pick up on sound waves that are much longer than the ones we pick up
14:17on.
14:18This means they can pick up on the movement of clouds and can physically hear when rain clouds are gathering.
14:24This is helpful to them because they will know when it's time to head down to water reservoirs, for example.
14:31Elephants also use infrasound to communicate with each other.
14:34They do that by pounding their feet on the ground.
14:37This sets up a powerful but hardly audible vibration.
14:41And since elephants are so awesome, they can pick up the vibration through nerve endings in their feet and ear
14:47bones.
14:48It works kind of like a bush telephone.
14:51Speaking of vibration, how do you think a snake can be enchanted by a flute if it doesn't have any
14:56ears?
14:57Well, the snake is not following the music.
15:00It's following the man's imperceptible foot tapping on the ground.
15:05You see, for humans, sound waves are usually carried by the air.
15:10But snakes, who move around through the ground, are connected to the environment by vibration.
15:16Snakes don't have eardrums, so their inner ear is connected to their jaw.
15:21Plus, the vibrations move from bone to bone inside a snake.
15:26This is called osteophany, which literally means that snakes listen with their bones.
15:31If this worked for humans, sound waves could literally send chills down someone's spine, huh?
15:38Okay, so humans listen through the air.
15:42Elephants and snakes can hear through the ground.
15:45How does hearing work for water animals?
15:48You could think that the water element impairs hearing, but not for dolphins.
15:53Dolphins emit extremely high-frequency sound waves that are classified as ultrasound.
15:58They emit clicking sounds to scan the water for food and other animals.
16:03Whichever way sound bounces back to them will help them identify what's in the water ahead and around them.
16:10To put it simply, dolphins see with their ears.
16:14This ability is called echolocation, and it's a form of navigation through sound.
16:22Well, you've heard of sonars, right?
16:25It's an instrument ships use to search for things underwater.
16:29A sonar emits very fast sound pulses that bounce off the seafloor and back.
16:34This way, they can detect the depth of the water.
16:37They can find shipwrecks, and even discover geological formations.
16:41That's pretty much what dolphins do to locate themselves.
16:45Oh, and if National Geographic is right, humans can hear frequencies up to 100 kilohertz when we are diving underwater.
16:53This means we can hear almost the same way as dolphins.
16:57Can you imagine using echolocation to wade through the water?
17:02Scientists don't exactly know why this happens, but they have two guesses.
17:06It might have something to do with how sound travels differently through the water.
17:10It can also have to do with the way our ears receive sound underwater and how our brain interprets it.
17:18Now, it's not only dolphins that can use sound to navigate through life.
17:22Bats can also do that.
17:24Since bats tend to live in dark or even pitch-black environments, they can't really count on their vision.
17:30But they have such precious hearing equipment that they might not even need to watch where they are going.
17:36Even though a bat's brain is tiny, it can thoroughly map the entire environment it is in and easily locate
17:43prey.
17:44What about rodents?
17:46If you've ever seen a mouse or a chipmunk bouncing around, you've probably thought they'd looked a bit accelerated.
17:52Here's a fun fact.
17:54Compared to humans, a chipmunk experiences reality at half the speed as we do.
17:59So what looks super fast and clumsy to us is seemingly pretty chill from that rodent's point of view.
18:05In terms of hearing, a mouse's hearing can go as high as 91 kilohertz, which is very, very high.
18:13Quite fascinating, huh?
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