White
0 dB / octave
Equal energy at every frequency. Because we hear in octaves, it sounds bright and hissy — the classic "TV static".
Sonic boom.
Faster than sound, an aircraft gives no warning: silence, then a double bang. Hear a jet below and above Mach 1, the Space Shuttle coming home, a whip crack and thunder.
Now playing
Deep sleep
Listen to the boom
Tap an example to play it, and again to pause; each one repeats every few seconds. The bangs are short and sharp: good speakers or headphones bring out the low end.
How a sonic boom happens
Anything moving through air sends out pressure waves at the speed of sound, about 343 metres a second (1235 km/h) at 20 °C. Slower than that, the waves run out ahead of it, so you hear a plane coming. Faster, it outruns its own waves: they pile up into a cone of compressed air trailing behind it, and on the ground you hear nothing until the cone sweeps over you.
Then the pressure jumps up at once, falls in a straight line below normal, and jumps back: an N-shaped wave, heard as a double bang from the nose and the tail. It is not a single bang at the moment a plane “breaks the sound barrier”: the boom is dragged along the ground for as long as it flies faster than sound, like the wake of a boat.
Facts that often get mixed up
- A boom is not made once, when the plane passes Mach 1. Everyone along its supersonic path hears it, in a strip of land that can be tens of kilometres wide.
- The pilot hears nothing: the boom trails behind the aircraft.
- Chuck Yeager first flew faster than sound in level flight, in the Bell X-1, on 14 October 1947. The whip got there long before: its crack is a tiny sonic boom.
- Supersonic airliners were kept off routes over land because of the boom. NASA’s X-59 is built to soften it into a quiet thump.
| Speed | What you hear | |
|---|---|---|
| Airliner | About Mach 0.85 | Engine noise as it approaches, no boom |
| Fighter jet | Mach 1.5 | Silence, a double bang, then the engines |
| Concorde | Mach 2 | A double boom, the two bangs about a third of a second apart |
| Space Shuttle landing | Supersonic until near the runway | Two distant booms and no engines: it landed as a glider |
| Whip | The tip passes Mach 1 | A sharp crack |
| Lightning | The heated air bursts out faster than sound | Thunder: a crack and a long rumble |
What causes a sonic boom?
An object faster than sound outruns its own pressure waves. They merge into a cone-shaped shock wave, and when the cone passes over you, you hear a sudden double bang.
Why is a sonic boom double?
The nose and the tail each make a shock wave. The pressure jumps up at the first, falls steadily, and jumps back at the second: two bangs a fraction of a second apart.
Can a sonic boom be quiet?
Shaping the aircraft can spread the pressure change out so it is gentler. NASA’s X-59 was designed to make a soft thump instead of a bang.
Mixes
Pick what you need. One tap to start, change anything and save it as your own.
Focus timer
Work in waves.
The Pomodoro rhythm: focus with calm sound in your ears, then take a real break. A soft bell marks every change, so you never watch the clock. Every fourth break is a long one.
Every fourth break is twice as long.
25:00Focus · 1 of 4
Sound while you work
Breathe
Slow your breathing down.
Follow the circle and the sound: it rises as you breathe in and falls as you breathe out. Choose a rhythm, or set your own, and pick what plays underneath.
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Sound while you breathe
Noise generator
Any color of noise, from deep brown to bright violet — and everything in between.
Brown noise
Spectrum · 20 Hz – 20 kHz
Sound science
The colors of noise
Same randomness, different tilt. Each color shifts energy between low and high pitches — here is what that sounds like.
Pink
−3 dB / octave
Equal energy in every octave, so it sounds even to the ear. Steady rain, rustling leaves. A favorite for focus.
Brown
−6 dB / octave
Deep and warm, like a distant waterfall or a plane cabin. Masks voices and traffic without any hiss.
Grey
Equal-loudness curve
Shaped around how our hearing works, so every pitch seems equally loud. Balanced and soft.
Blue
+3 dB / octave
The mirror of pink: more treble than bass. Airy, crisp, like a light spray.
Violet
+6 dB / octave
Mostly treble, like hissing water. Sometimes used to mask high-pitched ringing.
Calm
Gentle tones to settle into: singing bowls, a slow warm drone, wind chimes tuned so every note fits.
Frequencies
Famous tones on pages of their own: hear them side by side, with honest facts.
Sound phenomena
How sound bends, shifts, rings and fools the ear, and why space is silent: hear it for yourself.
Nature
Rooms & travel
Animals & countryside
A purring cat, whales and dolphins, a nightingale in the dark, cowbells on a summer pasture. Wonderful in stereo.
For babies
Womb sounds are what a baby heard for nine months: a deep rush of blood flow, and the heartbeat.
Hearing and speaker tests
Check your ears, headphones and speakers, each test on a page of its own with a live picture.
Ear Age · 60 seconds
Test your ears.
Our ears lose the highest pitches first, and it starts early. Find the highest tone you can still hear and see the typical age for it.
- Headphones on, quiet room
- Set a comfortable volume on the 1 kHz tone
- Don't turn it up when a tone disappears — that's the point
Step 1 · Volume
Play the reference tone and set your volume so it's clear but comfortable. Leave it there.
Step 2 · Listen
8,000Hz
Your result
8k12k16k20k
A rough guide, not a diagnosis. Your phone, headphones and even this browser can cut the highest tones. Worried about your hearing? See an audiologist.
More ear tests
Check your headphones, find the deepest bass your setup can play, or play any pitch you like.
Headphones check
Left & right
Each ear should get its own side. It matters for 8D, binaural beats and every stereo sound here.
Headphones on, then tap a side.
Bass test
How low can you go?
Deep tones from 200 Hz down to 20 Hz, the bottom of human hearing. Mostly it tests your speakers or headphones.
200Hz
Your setup plays down to
Tone generator
Any pitch, 20 Hz – 20 kHz
Hz
Start quiet: high tones and square waves get tiring fast.
Take it to bed
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Add Ears & Waves to your home screen and it opens like any app — full screen, with its own icon. Everything it needs is saved on your device, so it keeps playing on a plane, in a tent or with Wi-Fi off.
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