Topic
Sound questions for kids
Here are 194 questions about sound, music and hearing from 15 A Million Whys books, each with a short video answer. Book 14, The Sound Expedition is all about sound, music and hearing, and the rest come from other books in the series. Tap any question to watch the video and read the answer.
From Book 14: The Sound Expedition (150)
Why Does Every Sound Begin with Something Shaking?
Every sound begins with a vibration, which is something moving back and forth very fast! The shaking thing pushes on the air next to it, and that push spreads out as a wave.
Why Does Your Throat Tickle When You Hum?
Your throat tickles because tiny flaps inside it are fluttering super fast! Air from your lungs rushes past them, and they open and shut again and again.
Why Does a Ruler Buzz When You Flick It Off the Edge of a Desk?
A flicked ruler bends and springs back, over and over, and that makes a buzz! Each wiggle pushes on the air and makes a tiny sound.
What Is a Sound Wave Actually Made Of?
A sound wave is made of squeezed and stretched air! Where the air is squeezed, tiny particles bunch together, and where it is stretched, they spread apart.
Why Does a Slinky Show How a Sound Wave Moves?
A slinky is like a long row of air particles joined by springs! Push a few coils together, and the squeeze travels along it just like a sound wave.
How Are Water Ripples Like Sound Waves?
Water ripples and sound waves are alike because both carry energy without carrying stuff along! A ripple spreads in circles from where a pebble lands.
Why Does Rice Dance on Plastic Wrap When You Bang a Pot Nearby?
Rice dances on plastic wrap because sound waves make the wrap wiggle! The wiggling wrap bumps the rice grains up and down.
Why Does a Tuning Fork Keep Ringing for a While?
A tuning fork rings for a long time because its metal loses energy very slowly! After you tap it, the two prongs spring back and forth at the same steady rate.
Why Can You Feel Deep Bass Thumping in Your Chest?
You feel deep bass in your chest because low sounds are big, slow shakes! Those shakes are strong enough to make your skin and chest vibrate.
Why Does Pushing a Swing at Just the Right Moment Work So Well?
Pushing a swing at just the right moment works because a swing has its own natural rhythm! Push in time with that rhythm, and every push adds a little more motion.
Why Does a Tuning Fork Sound Louder When You Touch It to a Table?
A tuning fork sounds louder on a table because the whole tabletop shakes with it! A fork alone pushes only a tiny bit of air.
Why Can a Tin-Can Phone Carry a Voice?
A tin-can phone carries a voice because the string carries the shaking! Your voice makes the bottom of the cup vibrate.
What Does It Mean When We Say a Sound Has a Frequency?
Frequency tells you how many times something vibrates in one second! We measure it in a unit called hertz.
Why Do Puddles Shiver When a Heavy Truck Rumbles By?
Puddles shiver when a heavy truck rumbles by because the truck shakes the ground! The shaking spreads through the ground as waves.
Why Do Wood, Metal, and Glass Sound Different When You Tap Them?
Wood, metal, and glass sound different because they vibrate in different ways! Stiff, springy materials ring, and soft, squishy ones go thud.
Why Does a Bottle Hum When You Blow Across the Top?
A bottle hums when you blow across the top because the air inside starts to vibrate! Your breath makes the air in the bottle bounce back and forth.
Why Does a Fan Hum Higher When It Speeds Up?
A fan hums higher when it speeds up because its blades push the air more often! Each blade gives the air a little push as it passes.
Why Does a Card in Bicycle Spokes Make a Buzzing Motor Sound?
A card in bicycle spokes sounds like a motor because it clicks very quickly! Each spoke flicks the card once as the wheel turns.
Why Do Refrigerators Hum?
Refrigerators hum because a motor inside them shakes! The shaking spreads into the fridge's walls, and the walls push on the air.
Why Can You Hear a Mosquito's Wings but Not a Slowly Flapping Bird's?
You hear a mosquito's wings because they beat hundreds of times each second! That is fast enough to make a tone your ears can hear.
Why Do Sound Waves Push and Squeeze Instead of Going Up and Down?
Sound waves push and squeeze the air in the same direction the wave travels! That is different from water waves or a shaken rope.
Why Does a Stadium Wave Move Across the Crowd While the People Stay Put?
In a stadium wave, the wave travels while the people stay in their seats! Each person stands up and sits down in turn.
Why Do Two Nearly Matching Sounds Make a Wobbling Wah-Wah?
Two nearly matching sounds make a wobbling wah-wah because their waves keep lining up and canceling! You hear loud, then quiet, then loud again.
Why Can't We See Sound Waves?
We cannot see sound waves because they are tiny changes in air pressure, and our eyes cannot see air! But we can see what sound does.
Why Does a Fast-Shaking Object Look Blurry?
A fast-shaking object looks blurry because your eyes cannot follow motion that quick! Each wiggle takes only a fraction of a second.
Why Are Big Things Usually Lower in Sound than Small Things?
Big things are usually lower in sound because they swing back and forth more slowly! Slow vibrations make low sounds.
What Makes One Sound Louder than Another?
A sound is louder when the vibration is bigger! A larger back-and-forth swing pushes the air harder and carries more energy to your ears.
What Makes a Sound High or Low?
A sound is high or low because of its frequency, which is how fast it vibrates! A fast vibration makes a high pitch.
Why Do Mosquitoes Whine High While Bumblebees Buzz Low?
Mosquitoes whine high and bumblebees buzz low because of how fast their wings flap! A mosquito flaps hundreds of times each second.
Why Does a Ruler Twang Lower When More of It Hangs Over the Edge?
A ruler twangs lower when more of it hangs over the edge because the longer free end swings more slowly! Slower wiggles make lower sounds.
Why Does the Sound of Pouring Water Get Higher as the Glass Fills?
Pouring water gets higher in pitch as the glass fills because the air above the water gets shorter! Air in a shorter space vibrates faster, and faster vibrations sound higher.
What Do Decibels Measure?
Decibels measure how strong a sound is! We write the unit as dB.
Why Do 10 More Decibels Sound About Twice as Loud?
Ten more decibels sound about twice as loud because our ears work on a special scale! Each 10 decibels means about ten times more sound energy.
Why Does Cupping Your Hands Behind Your Ears Help You Hear?
Cupping your hands behind your ears helps you hear because it makes your ear funnel bigger! More sound waves get gathered and aimed into your ear canal.
Why Does Fresh Snow Make Everything Sound So Quiet?
Fresh snow makes everything sound quiet because it soaks up sound! It is full of tiny air pockets between the flakes.
Why Do Carpets and Curtains Make a Room Sound Quieter?
Carpets and curtains make a room quieter because they soak up sound! Their soft, fuzzy fibers trap sound waves.
Why Do Deep Rumbles Carry Farther than Squeaks?
Deep rumbles carry farther than squeaks because low sounds have long waves! Long waves spread widely and bend around things.
Why Can't We Hear a Dog Whistle?
We cannot hear a dog whistle because it makes sounds above 20,000 hertz! That is higher than humans can hear.
Why Would the Quietest Room in the World Feel Strange?
The quietest room in the world would feel strange because we are used to hearing some sound all the time! In a super-quiet room, you start to hear things inside your own body.
Why Is It Hard to Hear a Friend in a Noisy Room?
It is hard to hear a friend in a noisy room because their voice mixes with all the other sounds! Your ears and brain must pick out one voice from the rest.
Why Do People Talk Louder When It Is Noisy?
People talk louder in noisy places because their brains turn up their voices without them noticing! When it is noisy, you hear your own voice less.
How Can Two Sounds Cancel Each Other Out?
Two sounds can cancel each other out when their waves are exact opposites! Where one wave goes up, the other goes down.
Why Do Foghorns Make Deep Sounds?
Foghorns make deep sounds because low sounds travel farther! Low sounds also bend around obstacles.
Why Do Longer Wind-Chime Tubes Ring Lower?
Longer wind-chime tubes ring lower because each wiggle takes more time! A longer tube vibrates more slowly.
Why Can You Hear the Ocean in a Seashell?
The ocean sound in a seashell is not really the ocean! It is the quiet noise all around you, made louder by the shell's hollow space.
Why Does a Sound Seem Softer When You Are Farther Away?
A sound seems softer when you are farther away because it spreads out! Sound spreads in all directions like a growing ball.
Why Do You Hold Your Breath When You Try to Hear a Tiny Sound?
You hold your breath to hear a tiny sound because you stop making noise yourself! Your breathing and rustling clothes can cover up very quiet sounds.
Why Do Phone Calls Make Voices Sound Thinner?
Phone calls make voices sound thinner because a phone sends only part of your voice! It sends roughly the sounds between 300 and 3,400 hertz.
Why Do Sounds Seem Muffled Through a Wall?
Sounds seem muffled through a wall because most of the sound bounces back or gets soaked up! The part that gets through makes the wall vibrate a little.
How Can You Hear Someone Talking From Around a Corner?
You can hear someone talking from around a corner because sound waves bend and bounce! They spread out around the edges of doors and corners.
Why Does a Megaphone Make Your Voice Carry Farther?
A megaphone is a cone that gathers your voice and points it in one direction! Without a cone, your voice spreads out in every direction and gets thin fast.
Why Do Small Speakers Sound Thin and Big Speakers Sound Full?
A speaker makes sound by moving a cone in and out to push the air! Deep bass notes need a lot of air pushed slowly.
Why Does a Microphone Squeal When It Gets Close to a Speaker?
A microphone listens and a speaker talks, and sometimes they get stuck in a loop! The mic hears the speaker, and the speaker makes it louder again.
Why Does a Bell Keep Ringing After You Hit It?
A bell keeps ringing because the metal keeps vibrating after you hit it! Stiff metal springs back to its shape again and again.
Why Do Sirens Rise and Fall in Pitch?
Many sirens slide up and down in pitch on purpose! A changing sound is easier for our brains to notice than a steady one.
Why Does a Phone Buzz in Vibrate Mode?
A phone buzzes because a tiny part inside shakes the whole phone! The shaking pushes on the air and on whatever the phone is sitting on.
Why Are Vacuum Cleaners and Hair Dryers So Noisy?
Vacuum cleaners and hair dryers are noisy because fast fans push the air hard! The air races through narrow gaps and swirls in messy ways.
Why Do Some Quiet Electric Cars Hum on Purpose?
Some electric cars hum on purpose so that people can hear them coming! At slow speeds, these cars can be almost silent.
How Can a Needle in a Groove Play a Song?
A record has a wavy groove that is a copy of the sound wave! A needle rides in the groove and wiggles from side to side.
Why Does Snapping Your Fingers Make a Snap?
A finger snap is a fast, tiny slam that makes a crisp sound! Your middle finger slips off your thumb and hits the base of your thumb.
Why Does a Clap Make a Sharp Crack?
A clap makes a sharp crack because it creates a sudden pulse of air! Your palms squeeze the air between them and push it out in a flash.
Why Does Bubble Wrap Crack When You Squeeze It?
Bubble wrap pops because each bubble is a small pocket of trapped air! When you squeeze, the air inside is pushed harder and harder.
Why Does Velcro Make a Ripping Sound?
Velcro rips because thousands of tiny hooks let go of loops one after another! Each little release makes a tiny snap.
Why Does a Soda Can Go Psst When You Open It?
A soda can goes psst because gas rushes out when you open the tab! Inside, the gas is squeezed at a higher pressure than the air outside.
Why Do Ice Cubes Crackle in a Drink?
Ice cubes crackle because the ice gets stressed when it warms up quickly! The outside swells while the inside stays cold.
Why Does Rain Sound Louder on a Metal Roof than on Grass?
A metal roof acts like a giant drum when raindrops land on it! The whole thin sheet vibrates, and the sound spreads out.
Why Do Squeaky Doors and Sneakers Squeak?
Squeaks come from something called stick-slip! Two surfaces rub together, stick for a moment, and then slip free.
Why Does Wind Howl Around a House?
Wind howls when it swirls around corners and wires! The swirls peel off one after another at a steady rate.
Why Do Footsteps Sound Different on Different Floors?
Footsteps sound different because floors bounce, shake, or soak up sound in different ways! Hard floors sound sharp, wood floors boom, and carpet is hushed.
Why Does a Balloon Squeal When You Let the Air Out?
A balloon squeals because the stretched rubber flutters as air rushes by! It works a bit like your lips when you blow a raspberry.
Why Does a Spoon Hung on a String Sound Like a Big Bell?
A spoon on a string sounds like a big bell because the string carries the sound straight to your head! Solid things pass vibrations along better than air does.
Why Does a Phone Sound Louder in a Bowl?
A phone sounds louder in a bowl because the curved bowl bounces sound toward you! Sound that would have gone sideways gets pointed up and out, toward your ears.
Why Does Crunchy Food Sound So Loud When You Chew It?
Crunchy food sounds loud to you because the sound goes through your jaw bones to your inner ear! Bones carry sound very well.
Why Do Cars Need Mufflers?
Cars need mufflers because an engine makes very loud pulses of air! A muffler is a metal box that tames those pulses.
Why Does a Jar Lid Pop When You Open It?
A jar lid pops because air rushes in when the seal breaks! Inside a sealed jar, the air pressure is lower than outside.
Why Can't Sound Travel Through Empty Space?
Sound cannot travel through empty space because it needs something to pass through! Sound is a vibration that moves through air, water, or metal.
Why Does Sound Travel Faster in Water than in Air?
Sound travels faster in water than in air because water particles are packed much closer together! A vibration passes from one particle to the next more quickly.
Why Does Sound Travel Fastest Through Solid Metal?
Sound travels fastest through solid metal because its atoms are held tightly together! They snap back very quickly after a push.
Why Does a Siren Sound Higher as It Comes Toward You and Lower as It Goes Away?
A siren sounds higher as it comes toward you because the sound waves get squeezed together! After it passes, the waves are stretched out.
Why Can You Hear a Train Through the Rails Before You Hear It in the Air?
Sound moves much faster in steel than in air, so a train's rumble can race ahead through the rails! It arrives before the sound that travels through the air.
Why Does a Whip Crack?
A whip cracks because its tip moves faster than the speed of sound! A flick sends a loop racing down the whip.
Why Does a Jet Flying Faster than Sound Make a Boom?
A jet flying faster than sound makes a boom because its sound waves pile up into a shock wave! When that wave passes you, your ears hear a sudden loud boom.
Why Does Sound Carry Farther on a Cold, Still Morning?
Sound carries farther on a cold, still morning because the cold air bends it back down! Warm air lets sound move faster, and cold air slows it.
Why Do Voices Carry So Far Across a Calm Lake?
Voices carry far across a calm lake because the smooth water bounces sound instead of soaking it up! Cool air just above the water also bends sound back down.
Why Do Voices Sound So Strange Underwater?
Voices sound strange underwater because our ears are built for sound that arrives through air! Underwater, sound comes through the water and the bones of your head.
Why Is It Hard to Tell Where a Sound Is Coming From Underwater?
Underwater it is hard to tell where a sound comes from, because sound travels so fast! The time difference between your two ears becomes tiny.
Why Does Bass Travel Through Walls When High Sounds Don't?
Bass travels through walls because low sounds have long, slow waves that shake a whole wall at once! High sounds have short waves that bounce off or get soaked up.
Why Is Sound a Little Faster on a Hot Day?
Sound is a little faster on a hot day because warm particles move faster! They bump into each other more quickly.
How Fast Does Sound Travel?
Sound travels about 343 meters every second in air at room temperature! That is about 1,235 kilometers an hour.
Why Can a Long Tube Carry a Whisper?
A long tube can carry a whisper because it keeps the sound from spreading out! The sound waves bounce along inside the walls and stay together.
Why Can Astronauts Talk to Each Other on a Spacewalk?
Astronauts can talk on a spacewalk because they use radio instead of sound traveling through air! A microphone turns their voice into an electrical signal.
Why Do Scuba Divers Use Hand Signals Instead of Talking?
Scuba divers use hand signals because they cannot talk with a breathing tool in their mouths! Sounds underwater are also hard to understand.
Why Do Highways Have Tall Walls Beside Them?
Tall walls beside highways are noise barriers that keep traffic sound away from homes! They block, reflect, and sometimes absorb sound waves.
Why Can a Whisper Travel Along a Curved Wall?
A whisper can travel along a curved wall because the sound clings to the curve! The waves bounce along the wall again and again.
Why Does a Plane Seem to Be in a Different Place than Its Sound?
A plane seems to be in a different place than its sound because sound is slower than the plane! What you hear left the plane a while ago, even though the plane looks close.
Why Does a Crowd of People Sound Like a Steady Roar?
A crowd sounds like a steady roar because many voices blend into one smooth noise! The voices are at different pitches and at different times.
Why Do Voices Sound Thin High Up on a Mountain?
Voices can sound thin high on a mountain because thin air and open spaces make sound fade fast! Up high, the air has fewer particles in each puff.
Why Does Snow Squeak When It Is Very Cold?
Snow squeaks in very cold weather because the crystals are hard and dry! When you step on them, they crush and rub in rapid-fire.
Why Does a Frozen Lake Sometimes Make Strange Pew-Pew Sounds?
A frozen lake can make pew-pew sounds because cracking ice sends waves through the ice! High notes travel faster than low notes in ice.
Why Do Some Beaches Have Singing Sand?
Singing sand makes sounds because layers of sand grains slide over each other together! That slipping makes a steady vibration.
Why Can You Hear a Clear Echo in a Canyon but Not in a Forest?
An echo is a sound that bounces off a hard surface and comes back to you! In a canyon, tall flat rock walls send your voice straight back.
Why Does Your Voice Sound Bigger in a Bathroom?
Your voice sounds bigger in a bathroom because hard walls bounce it back and forth! Those quick bounces blend with your real voice, so it seems fuller.
Why Does a Shout in a Tunnel Keep Ringing?
A sound in a tunnel keeps ringing because the walls, floor, and ceiling are all hard! The sound bounces back and forth along the whole tunnel.
How Can You Use an Echo to Measure Distance?
An echo is a sound's round trip, and you can use its trip time to measure distance! The sound goes to a wall and comes back, so it travels there and back.
Why Do Car Parking Sensors Beep Faster as the Car Gets Closer?
Parking sensors beep faster because the echo returns sooner when you get closer! The sensors send out short bursts of sound too high for us to hear.
How Can Some People Use Clicking Sounds to Sense Walls and Doorways?
Some people use soft clicking sounds to sense walls and doorways. This is called echolocation!
What Is Ultrasound, and How Do Bats and Doctors Use It?
Ultrasound is sound with a pitch so high that people cannot hear it! The waves are still real, and they travel through air, water, and the body.
Why Can a Shout Take Seconds to Bounce Back From a Far-Away Mountain?
A shout takes seconds to come back from a faraway mountain because sound needs time to travel! Sound is fast, but mountains can be very far away.
Why Do Recording Studios Have Foam Wedges on the Walls?
Recording studios have foam wedges on the walls to soak up sound instead of letting it bounce! With fewer echoes, a studio can record clear sound without a roomy ring.
Why Can't You Hear an Echo in a Small Room?
You cannot hear a clear echo in a small room because the walls are so close! The echo comes back almost at once and blends with your voice.
Why Does Clapping Between Two Flat Walls Make a Zinging Sound?
Clapping between two flat walls makes a zinging sound called a flutter echo! The sound bounces back and forth between the walls, and each bounce is a tiny echo.
Why Can Tapping a Wall Tell You Where the Hidden Beams Are?
Tapping a wall can tell you where the hidden beams are, because hollow and solid parts sound different! Behind a wall there are hollow spaces and hard wooden beams.
Why Do People Tap Things to Check If They Are Cracked or Hollow?
People tap things to check if they are cracked or hollow, because flaws change how an object rings! A solid object rings clearly when you tap it.
How Do Plumbers Find a Leak in a Pipe Using Sound?
Plumbers can find a leak in a pipe by listening for the sound the leak makes! Water under pressure squirts through a tiny crack with a hissing noise.
How Can Scientists Use Sound to Measure How Thick Ice Is?
Scientists can measure how thick ice is by sending sound into it and timing the echo! A short pulse of sound goes down and bounces off the bottom of the ice.
Why Can You Tell How Big a Room Is with Your Eyes Closed?
You can tell how big a room is with your eyes closed because every room has its own sound! A big room has longer echoes and a lingering sound.
Why Do You Sometimes Hear Your Own Voice Echo on a Phone Call?
You hear your own voice echo on a phone call because your words make a round trip! They travel to your friend, come out of their speaker, and get picked up by their microphone.
Why Did Sailors Blow a Horn Near Cliffs and Listen for the Echo?
Sailors blew a horn near cliffs to use the echo as a safety check in fog! When they could not see the shore, the echo told them how close it was.
Why Does Your Voice Sound Hollow Inside a Bucket or a Big Pipe?
Your voice sounds hollow in a bucket or a big pipe because the air inside rings along with you! A bucket or pipe is a small hollow space with hard sides.
How Can Sound Waves Clean Eyeglasses?
Sound waves clean eyeglasses in a machine called an ultrasonic cleaner! It is a small tank of soapy water with a device that sends in sound too high to hear.
Can a Singer Really Break a Glass with Their Voice?
A singer really can break a glass with their voice, but only in rare cases! Every glass has its own natural pitch that it likes to ring at.
Why Can Sound Hold Tiny Bits of Foam in Mid-Air?
Sound can hold tiny bits of foam in mid-air. This is called acoustic levitation!
Why Does Sand Make Patterns on a Vibrating Plate?
Sand makes patterns on a vibrating plate because some parts shake and some parts stay still! The sand bounces away from the shaking parts.
Why Do Some Backing-Up Trucks Go Shh-Shh Instead of Beep-Beep?
Some backing-up trucks go shh-shh instead of beep-beep because a shh sound is easier to locate! A beep has just one pitch, and it is hard to tell where it comes from.
Why Can Echoes Make a Speech Hard to Understand?
Echoes make a speech hard to understand because each sound lingers and overlaps the next one! The words blur together like wet paint.
What Do the Tiny Hair Cells in Your Ears Do, and Why Can't They Grow Back?
Tiny hair cells in your inner ear turn sound into signals for your brain! They cannot grow back in people, so loud noise can cause lasting harm.
Why Do People Who Work Near Loud Machines Wear Ear Protection?
People who work near loud machines wear ear protection to keep their hearing strong for life! Lawn mowers, power saws, and drills can be so loud that long listening...
Why Do Ear Defenders Matter at Fireworks, Motor Races, and Loud Concerts?
Ear defenders matter at fireworks, motor races, and loud concerts because those sounds are very strong, and they can be too much for your ears! Ear defenders turn the volume down so you can enjoy the show comfortably and safely.
How Can You Tell If Your Headphones Are Too Loud?
You can tell your headphones are too loud with a simple rule! If a friend an arm's length away can hear your music, it is too loud.
Why Do Listening Breaks Help Your Ears?
Listening breaks help your ears because the hair cells get tired after a lot of sound! Resting them in a quiet place gives them time to recover.
Why Do Your Ears Sometimes Ring After a Very Loud Noise?
Your ears can ring after a very loud noise because the tiny hair cells in them got tired out! The ringing is your ears' way of saying, "that was too loud." It is a...
Why Do Hearing Tests Use Beeps in Headphones?
Hearing tests use beeps in headphones to find the quietest sound you can hear! The test is called an audiogram, and it does not hurt at all.
How Does a Hearing Aid Work?
A hearing aid is a tiny device worn in or behind the ear that makes sounds easier to hear! It has a microphone, a small computer, and a tiny speaker.
Why Do Captions on Videos Help Lots of People?
Captions on videos help lots of people because they show the words on screen! They help people who are Deaf or hard of hearing follow along.
Why Do Ears Make Earwax?
Ears make earwax to keep themselves clean and healthy! Earwax, also called cerumen, is a sticky, slightly oily layer in your ear canal.
Why Shouldn't You Poke Anything Into Your Ears?
You should not poke anything into your ears because the eardrum inside is thin and delicate! Cotton swabs, pencils, and fingers can scratch the ear canal.
Why Are Our Outer Ears Shaped Like Curly Funnels?
Your outer ears are shaped like curly funnels to catch sound and help you find where it comes from! The curves and ridges catch sound waves and bounce them into the ear canal.
Why Do Some Crosswalks Beep or Chirp?
Some crosswalks beep or chirp so that people who are blind or have trouble seeing know when it is safe to cross! The sounds say when the walk signal is on.
Why Do Some Alarms Flash a Light as Well as Make a Sound?
Some alarms flash a light as well as make a sound because light is another way to share a warning! A flashing light can warn people who are Deaf or hard of hearing.
Why Does Background Noise Make It Harder to Focus?
Background noise makes it harder to focus because your brain only has so much attention to share! When there is chatter around, your brain tries to listen to it and to do your work at the same time.
Why Is It Risky to Wear Headphones While Biking or Crossing the Street?
It is risky to wear headphones while biking or crossing the street because you may not hear warning sounds! Your ears are part of your safety team.
Why Can Younger People Hear Some Sounds That Adults Can't?
Younger people can hear some high sounds that adults can't! Babies and young people can hear higher pitches than most adults.
How Can You Make a Noisy Room Quieter?
You can make a noisy room quieter by adding soft things that absorb sound! Rugs, curtains, cushions, and bookshelves full of books all soak up sound.
What Is White Noise, and Why Does It Hide Other Sounds?
White noise is a sound that has every pitch mixed in at about the same strength! It sounds like shhhh or the hiss of a TV between channels.
How Do Vibrating Alarm Clocks and Flashing Doorbells Help People Who Are Deaf or Hard of Hearing?
People who are Deaf or hard of hearing often use alerts that they can see or feel instead of sounds! A vibrating alarm clock can shake the bed or pillow.
How Can People Who Are Deaf or Hard of Hearing Enjoy Music?
People who are Deaf or hard of hearing can enjoy music in many ways! Music is more than just hearing sound.
Why Should You Tell a Grown-Up If Your Ears Hurt or Sounds Seem Muffled?
You should tell a grown-up if your ears hurt or sounds seem muffled, because something may be wrong! Most ear troubles can be treated.
Why Do Some Toys and Kids' Headphones Have a Volume Limit?
Some toys and kids' headphones have a volume limit to protect young ears! Many have a limit of about 85 decibels, and some use lower limits.
Why Do Some Animals Have Giant Ears?
Some animals have giant ears because big ears catch faint sounds from far away! A bigger ear collects more sound waves, like a larger bucket collects more rain.
What Is the Faintest Sound a Person Can Hear?
The faintest sound a person can hear is called the threshold of hearing! For most healthy people, that is about zero decibels at middle pitches.
From Book 1: The Great Expedition (4)
Why Do Whales Sing? Songs That Travel for Miles!
Whale songs are some of the ocean's most amazing sounds! Sound travels far in water, and the page says whale songs can travel for miles.
Why Do Bats Use Sound to Hunt? Echoes in the Dark!
Night is hard to hunt in by eye, so bats use sound! They make high-pitched clicks with their mouth or nose, and the clicks bounce back as echoes.
Why Do Echoes Bounce? Sound Bounces Back Late!
Shout at a far wall and your voice comes back to you! Sound starts with vibrations and travels through the air in waves, and when a wave hits a hard surface it reflects, bouncing back the way it came.
How Do Headphones Make Sound? Shaking Air Into Music!
Music from headphones starts as electricity. The music player sends an electrical pattern through the cable that matches the song, and that pattern makes a coil and...
From Book 2: The Inside Expedition (6)
Why Do Songs Get Stuck in Our Head?
Have you ever had a song play again and again in your head, even when you wanted it to stop? That's an earworm!
Why Do Sudden Sounds Make Us Jump?
Have you ever jumped when a door slammed nearby? The alarm path is faster than thinking!
Why Does Music Give Some People Chills?
Has a song ever made your arms tingle or your skin get goosebumps? Those are music chills.
Why Does Music Change Our Mood?
Music is sound, and sound can poke the part of your brain that handles feelings. The beat, the pitch, and your own memories can all change how you feel.
Why Does Darkness Make Hearing Feel Sharper?
In the dark, it feels as if your hearing gets sharper. Your ears did not change, though.
Why Does Our Own Voice Sound Different?
Your own voice sounds different on a recording. When you talk, you hear yourself through the air and through the bones of your skull.
From Book 3: The Built Expedition (7)
Why Does a Kettle Whistle?
Boiling water makes steam. The steam must escape through a small spout hole.
Why Do Radios Play Music From Far Away?
A radio station shakes electric waves into the air, and your radio catches those waves and turns them back into sound. Sound is too weak to travel for miles.
Why Do Speakers Make Sound?
A speaker has a paper or plastic cone that pushes air. And pushing air in a pattern is exactly what sound is!
Why Does a Whistle Get So Loud?
A whistle is a tiny wind instrument. Your breath slams into a sharp edge and a small chamber, which chops the air into fast pulses that your ears hear as a piercing tone.
Why Do Drums Boom?
A drum is a stretched skin, or plastic head, over a hollow body. A hit makes the head bounce, and that bounce shoves a big gulp of air into a booming sound wave.
Why Does an Echo Come Back?
An echo is a sound's return trip. Sound is a wave in the air, and a hard wall can bounce the wave back, a little bit late, so you hear yourself twice.
Why Do Referees Use Whistles?
A whistle is like a tiny, super loud speaker. Its sharp blast cuts through crowd noise.
From Book 4: The Wild Expedition (8)
Why Is a Forest Quiet, Then Loud?
A forest is full of living sound-makers that clock in at different hours. Midday can feel hushed, while dawn and dusk can roar with birds, frogs, and insects.
Why Do Cicadas Buzz So Loud?
That loud summer roar is a male cicada calling for a mate! Ribs in his abdomen click so fast that they make a buzz that can travel across a whole yard.
Why Do Birds Sing?
A bird song is a message! Many birds sing to claim a territory and to find a mate.
Why Does a Stream Make a Bubbling Sound?
Moving water slams into rocks and folds over itself! Air gets trapped in the water and pops.
Why Is the Forest Louder at Night?
For many animals, night is rush hour. Frogs, insects, owls, and mammals that hide by day clock in for their night shift.
Why Do We Hear Coyotes at Night?
Howls and yips are messages. Coyotes use them to say, we are here, and to keep in touch with family and neighbors.
Why Do Night Insects Sound Like a Band?
Crickets, katydids, and some frogs all clock in as night singers. Each species has its own instrument and its own pattern and tempo.
Why Do We Hear More When We Stop Walking?
Your own feet, jacket, and whispers are like a marching band. When you freeze, that band stops, and the real woods can reach your ears.
From Book 6: The Ocean Expedition (2)
Why Do Some Whales Sing?
Some whales, especially male humpbacks, make long, patterned sounds called songs. Songs may help whales find a mate, or keep in touch across the sea.
Why Do Scientists Use Sonar?
Sonar sends out a ping of sound, and then listens for the echo. The time the echo takes to come back tells how far away something is.
From Book 9: The Food Expedition (2)
Why Do Some Smells Seem ‘Loud’ Even in Tiny Amounts?
Some smells seem loud even in tiny amounts because human noses can detect some molecules at super-low doses! Smells like toasted bread or vanilla are easy to notice.
Why Does Bread Sing When It Cools?
Fresh bread can sing when it cools because the crust crackles as it changes! The crackling sounds like a tiny song.
From Book 10: The Body Expedition (6)
Why Does Cracking Knuckles Make Noise?
Knuckles can make a popping noise because of tiny gas bubbles in the fluid inside your joints! When a joint stretches, a bubble can pop, and you hear a little crack.
Why Can a Stethoscope Let You Hear a Heartbeat?
A stethoscope lets you hear a heartbeat because it carries sound from your chest right to a doctor's ears! Heart sounds are quiet, so the tubes help guide them.
Why Can a Favorite Song Give You Chills?
A favorite song can give you chills because music you love can make your brain release feel-good chemicals! Surprising or powerful moments in a song can set off goosebumps.
Why Does Loud Noise Risk Hearing?
Loud noise can harm your hearing because the tiny hair cells in your inner ear are delicate! Very loud sound can damage them, and they do not grow back.
Why Is It Okay to Cover Your Ears When a Siren Is Very Loud?
It is okay to cover your ears when a siren is very loud because very loud sound can hurt your ears. Covering them turns the volume down.
Why Does Closing Your Eyes Make You Notice Sounds More?
Closing your eyes makes you notice sounds more because your brain has less to look at. Your attention can shift to hearing, almost like turning a spotlight toward sound.
From Book 11: The Animal Expedition (1)
From Book 12: The Volcano Expedition (1)
From Book 17: The Rainforest Expedition (3)
Why Is a Rainforest So Loud?
A rainforest is packed with animals that call, buzz, and chirp. Frogs sing, insects click and hum, birds shout, and monkeys howl.
How Can a Frog Smaller than Your Thumb Be So Loud?
A tiny frog can be loud because it uses its whole body like a speaker! The coquí frog of Puerto Rico is about the size of a quarter.
How Do Scientists Use Sound Recorders to Listen to a Rainforest?
Scientists listen to the rainforest by hanging sound recorders in the trees! The recorders listen for days or weeks, even when no one is there.
