White
0 dB / octave
Equal energy at every frequency. Because we hear in octaves, it sounds bright and hissy — the classic "TV static".
Auditory illusions.
A beat that speeds up for ever, tone pairs that rise for some listeners and fall for others, and two illusions that put sounds in the wrong ear. Listen, then compare with a friend.
Now playing
Deep sleep
Listen and be fooled
Tap an example to play it, and again to pause. The octave and scale illusions need headphones. For the tritone paradox, decide for each pair whether it goes up or down, then ask someone else.
How these illusions work
The Risset rhythm does for tempo what the Shepard tone does for pitch. The same beat plays in several layers, each twice as fast as the one below. As they all speed up, the fastest layer fades out and a new slow one fades in, so after ten seconds the sound is exactly where it started, though it seemed to accelerate the whole time. Jean-Claude Risset, who also made the endless glissando, described it.
The other three are Diana Deutsch’s. In the tritone paradox, two Shepard tones half an octave apart can be heard rising or falling, and people disagree, partly depending on the speech they grew up with. In the octave and scale illusions, the brain sorts tones into tidy high and low lines, and hears them in the wrong ears.
Good to know
- In the tritone paradox, Deutsch found that people from California and from the south of England tended to hear the same pairs in opposite directions.
- In the octave illusion most right-handed people hear the high tone in the right ear and the low one in the left, whichever ear it really comes from.
- Tchaikovsky wrote a scale illusion into his Sixth Symphony: the first and second violins trade notes, but the audience hears two smooth lines.
- Nothing is wrong with your ears: these illusions show the shortcuts the brain takes to group sounds into lines, the same ones that let you follow one voice in a noisy room.
| What plays | What most people hear | |
|---|---|---|
| Risset rhythm | One beat in five layers, all speeding up, fading in at the bottom and out at the top | A beat that never stops accelerating |
| Tritone paradox | Pairs of Shepard tones half an octave apart | Up for some listeners, down for others |
| Octave illusion | 400 and 800 Hz taking turns, the opposite one in each ear | A high tone in one ear taking turns with a low tone in the other |
| Scale illusion | A scale up and a scale down at once, the notes alternating between the ears | A high melody in one ear and a low one in the other |
What is the Risset rhythm?
A rhythm that seems to speed up, or slow down, for ever. Layers of the same beat at doubled tempos fade in and out, so the pattern loops while sounding like a constant accelerando.
What is the tritone paradox?
Two tones half an octave apart, made so that their octave is ambiguous. Some people hear the pair rising, others falling, and the split follows where they grew up.
Do I need headphones?
For the octave and scale illusions, yes: each ear must get its own tones. The Risset rhythm and the tritone paradox work on speakers.
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.
- PrivateNo account, no ads, no cookies. Your mixes stay on your device.
