Skip to story
ELI5 Yahaaa

Tag

Sound

Noise, music, echoes, and hearing — 44 tiny stories across 7 shelves.

Everyday wonders

Kitchen, bubbles, echoes, and odd little magic — 11 stories.

All everyday wonders →

Your body is already predicting

Why Is It Hard to Sit Still to Music?

Muscles answer about a fifth of a second late, so clapping on the beat means deciding before it arrives. A crowd syncs without arranging anything.

Let’s go →

A skin that shoves the air

How Does a Drum Make a Sound?

A string's wobbles line up into a note; a round skin's do not, so a drum reads as a hit. The middle thuds, the edge rings and the rim gives a crack.

Let’s go →

Sound coming back

What Is an Echo?

An echo is sound bouncing off a surface and reaching you a second time, late enough — over about a tenth of a second — to be heard as separate.

Let’s go →

Far, hard and facing you

Why Do Canyons Echo So Well?

A wall has to be at least 17 metres off before you hear its echo separately. Bare rock reflects nearly all the sound where a forest would swallow it.

Let’s go →

Nothing left to absorb sound

Why Are Empty Rooms So Echoey?

Furniture and curtains swallow sound. Strip a room bare and every reflection keeps bouncing, smearing speech into the mush you hear in an empty flat.

Let’s go →

Thickness, tightness, length

Why Do Guitar Strings Sound Different?

Only three things about a string decide the note it makes — how thick it is, how tight, and how long — and a guitar lets you change all three.

Let’s go →

Faster sound, same vibration

Why Does Helium Make Your Voice Squeaky?

Sound travels far faster in helium, so the resonances of your unchanged throat leap upward. Your vocal cords carry on buzzing at exactly the same pitch.

Let’s go →

A muscle misfiring

What Causes Hiccups?

An irritated nerve jerks the diaphragm into an unplanned gulp, and about 35 milliseconds later the vocal cords snap shut on it. That snap is the sound.

Let’s go →

Eighty-eight little catapults

What Happens Inside a Piano?

A piano key does not push the hammer onto the string. It throws the hammer and lets go in mid-air, so the note is free to ring afterwards.

Let’s go →

Notes that share their wobbles

Why Does Singing Together Sound Good?

Two notes slightly apart make a throbbing that singers use to tune themselves, and a choir drifts into agreement until even the breathing lines up.

Let’s go →

The same note, a different mix

Why Does a Piano Not Sound Like a Violin?

A flute and a violin can play exactly the same note and never be confused, because each adds its own mix of quieter higher notes above it.

Let’s go →

Animals

Creatures on land, in the sea, and in the air — 10 stories.

All animals →

Shouting at the world and listening back

How Does a Bat See in the Dark?

A bat crosses a pitch-black cave by shouting too high for you to hear and timing the echoes — and its wings are hands with enormous fingers.

Let’s go →

A comb and a scraper

How Does a Cricket Chirp?

A cricket does not chirp with its mouth. It scrapes a hard wing edge over a comb of ridges, and listens with eardrums in its front legs.

Let’s go →

A picture built from echoes

How Do Dolphins See With Sound?

A hollow ball and a solid one ring differently, so a dolphin hears what a thing is made of and not merely where it is — hundreds of times a second.

Let’s go →

Shout, listen, measure

How Do You See With Sound?

Echolocation is measuring distance by timing an echo — and bats, dolphins, ships and hospital scanners all do the same arithmetic.

Let’s go →

A nose with forty thousand muscles

What Can an Elephant Do With Its Trunk?

An elephant's trunk is a boneless nose and upper lip with tens of thousands of muscles, used to breathe, drink, grab, smell and talk.

Let’s go →

Catching what you cannot see

How Does a Fox Hunt Under Snow?

A fox catches a mouse it never sees by comparing what each ear hears, tilting until it has the depth, then diving head-first at the sound.

Let’s go →

An argument without a fight

Why Does a Gorilla Beat Its Chest?

Chest-beating is an honest advertisement of size, carried far enough that a rival can decide to back down long before anybody has to get hurt.

Let’s go →

Hearing in three dimensions

How Do Owls Hunt in the Dark?

An owl's ears sit at deliberately different heights, so a sound reaches one a fraction before the other. That gap is enough to locate a mouse in the dark.

Let’s go →

No lips, no teeth, no vocal cords

How Does a Parrot Talk?

A bird's voice box sits at the fork of its windpipe, so each branch works separately and some birds hold two notes at once — a duet with themselves.

Let’s go →

Radiators that also listen

Why Do Rabbits Have Such Big Ears?

Related animals in hot places grow bigger ears, legs and noses the world over — a desert jackrabbit's run to about a quarter of its own body length.

Let’s go →

Physics

Invisible forces you can play with — 8 stories.

All physics →

Waves bunched and stretched

Why Does a Siren Change Pitch as It Passes?

To the driver the siren never changes at all. Light does the same thing, which is how a receding galaxy shifts red and betrays an expanding universe.

Let’s go →

How big the push is

What Makes a Sound Loud?

Loudness is how hard the air gets shoved; pitch is how often. The two are entirely independent, which is why a whisper and a shout can hit the same note.

Let’s go →

Counting wiggles

What Makes a Sound High or Low?

Fast vibrations sound high and slow ones sound low. That is the whole of pitch — a count of wiggles per second, and nothing more complicated.

Let’s go →

Pushing in time

Why Does One Note Rattle the Window?

Every object has a rhythm it swings at naturally. A sound matching that rhythm adds a push on every swing, so tiny pushes build into a rattle.

Let’s go →

Air, pushed

How Does Sound Travel?

Sound is not a thing that flies. It is a squeeze handed from one air molecule to the next, passed all the way along to your eardrum.

Let’s go →

Fifteen times faster through steel

Sound Goes Faster Through a Wall Than Through Air

Sound travels by particles shoving their neighbours, so the stiffer the material the faster the shove passes — steel beats water, and water beats air.

Let’s go →

Squeeze and stretch

What Does a Sound Wave Look Like?

Each patch of air only shuffles back and forth a fraction of a millimetre, passing the squeeze along at 343 metres a second. Nothing travels with it.

Let’s go →

Wobbling back to the middle

Why Do Things Vibrate?

Push something springy out of shape and it overshoots the middle coming back, then overshoots again. Match its natural rate and the swing keeps growing.

Let’s go →

How things work

Everyday machines, taken apart — 6 stories.

All how things work →

Life & body

Seeds, hearts, senses, and growing things — 5 stories.

All life & body →

Earth & sky

Weather, light, and the air around us — 3 stories.

All earth & sky →

Space

Crashy night-sky stories — 1 story.

All space →