White
0 dB / octave
Equal energy at every frequency. Because we hear in octaves, it sounds bright and hissy — the classic "TV static".
Infrasound: below hearing.
Below 20 Hz sound is too low to hear, yet elephants talk in it and storms, volcanoes and whales fill the air with it. Hear an 18 Hz tone, and infrasonic calls raised into hearing.
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Deep sleep
Listen below hearing
Tap an example to play it, and again to pause. Phone and laptop speakers cannot play 18 Hz: you will hear nothing, or a faint buzz. Headphones or a subwoofer can, and you may feel it more than hear it. Keep the volume moderate.
What infrasound is
Infrasound is sound below about 20 Hz, under the lowest note we hear as a tone. It is still sound, air pushed back and forth, only so slowly that the ear cannot follow it as pitch. Very loud, it is felt as pressure or flutter. Long waves lose little energy in air, so infrasound travels hundreds and even thousands of kilometres.
Nature makes a great deal of it: storms, ocean waves, earthquakes, volcanoes and meteors. Elephants call each other with rumbles as low as 14 Hz, and blue whales sing at about 10 to 40 Hz. To hear such calls, scientists speed recordings up or raise them by several octaves, as some examples here do.
Facts that often get mixed up
- There is no “brown note”: no infrasound has been shown to make people lose control of their bowels.
- Hearing does not end at a wall at 20 Hz. Below it, sound has to be very loud, around 80 to 100 dB, to be noticed at all, and then it is felt as pressure and flutter rather than heard as pitch.
- A worldwide network of infrasound stations listens for nuclear explosions under the test-ban treaty. It also picks up meteors, volcanoes and rocket launches.
- In 1998 the engineer Vic Tandy traced the unease in a “haunted” lab to a fan making about 19 Hz. It is a famous story, but a single case, not a proven cause of ghost sightings.
| Frequency | How far it carries | |
|---|---|---|
| Elephant rumble | From about 14 Hz | A few kilometres |
| Blue whale | About 10 to 40 Hz | Hundreds of kilometres through the ocean |
| Thunder | Much of its energy below 20 Hz | Tens of kilometres |
| Wind turbine | About 1 Hz and its harmonics, from the blades | Usually far below what people can sense |
| Volcanoes and meteors | Down to a fraction of a hertz | Round the world: the 2013 Chelyabinsk meteor was picked up across the globe |
What is infrasound?
Sound with a frequency below about 20 Hz, too low to be heard as a tone. Storms, the sea, earthquakes, volcanoes, large animals and machines make it.
Can humans hear infrasound?
Not as pitch. Very loud, it can be felt as pressure or a fluttering, and some people notice it as unease; at everyday levels it goes unnoticed.
Why can’t I hear the 18 Hz example?
Most phone and laptop speakers cannot move enough air to play it. Headphones or a subwoofer can, and even then it is felt more than heard.
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.
Ready
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
An app without the app store.
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.
Preparing offline mode…
- Works offlineNo streaming. Sound is computed on your device, forever.
- Screen offKeeps playing with the phone locked. The timer fades it out gently.
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