Sleep sounds
White noise for sleep
Most people who type this into a search box want one of two things, and they are not the same thing. Some want to drown out a neighbour. Some want to quiet their own head. White noise is very good at the first job and only sometimes good at the second.
In short
White noise holds equal power in every one hertz band, which makes it the brightest of the sleep noises and the best at covering thin, sharp sounds: keys in a lock, a running tap, a voice through a wall. That same brightness is why plenty of people last about an hour before switching to pink or brown.
- Roll-off per octave
- 0 dBRoll-off per octaveFlat power per hertz. Nothing falls away, which is the entire definition.
- Coloured noises in Tock
- 8Coloured noises in TockWhite, pink, brown, gray, blue, violet, green, and a pink that slowly breathes.
- Layers at once
- 4Layers at onceStack up to four, then save the stack as a mix you can reopen.
Flat per hertz is not flat to your ear
The textbook definition is simple: equal power in every one hertz slice of the spectrum. The band from 100 to 101 Hz carries the same energy as the band from 10,000 to 10,001 Hz.
Your hearing does not work in one hertz slices, though. It works roughly in octaves, and every octave you climb is twice as wide as the one below it. Twice the bandwidth at the same power density means twice the energy, so measured per octave, white noise actually rises about 3 dB with every step up. That climb is the hiss.
This is the single fact that explains why white noise sounds bright even though its spectrum is described as flat.
It raises the floor, it does not cancel anything
A door closing at 2am wakes you because of the jump, not the volume. You were sitting in a near-silent room and something arrived 30 dB above it. Put a steady bed in the room and that same door is now maybe 10 dB above the floor, which is a much smaller event for your sleeping brain to react to.
That is all masking is. Nothing gets removed, quieted or cancelled. If you need sound to actually go away, that is earplugs, and no app can do it.
Tock builds it a sample at a time
White noise is one of the 41 sounds Tock synthesises on your phone rather than playing back from a file. Nothing downloads, nothing streams, and nothing repeats, because there is no loop to come back around.
That matters more than it sounds like it should. Once you have noticed a seam in a looping track, you cannot stop noticing it, and 3am is exactly when you go looking.
Brightness is the thing to keep an eye on
Volume matters more for white noise than for anything lower, because the energy is concentrated where your ear is most sensitive. Set it just loud enough that the sound you are covering stops being an event, and no louder. If you can hold a conversation over it comfortably, it is probably about right.
If white sounds harsh but you still want the cover, Tock also ships gray noise, which is white shaped by the inverse of the ear's own sensitivity curve so it measures uneven and sounds even. For a lot of people that is the one to reach for before pink.
- Far, Near and Close move the bed back and forward with a real filter, not a volume slider
- Maskers like this one can run until your alarm rather than fading out
- A mix of four is the ceiling, which is more than enough and stops the stack turning to mud
Who it suits, and who it does not
Worth trying if
- Thin, sharp intrusions: keys, taps, cutlery, a voice carrying through a stud wall
- Rooms where the problem is sudden rather than constant
- People who already know they sleep fine through a bright hiss
- A neutral starting point, before you decide whether you want pink or brown instead
Probably skip it if
- Traffic, a bass-heavy TV downstairs, or a rumbling AC unit, where brown noise does more at lower volume
- Light sleepers who find high frequencies tiring after an hour, which is far more common than the internet lets on
- Sharing a bed with someone sensitive to brightness, because the top end travels across a room and a rumble does not
How it behaves once it is running
- Tock generates it on device, sample by sample, so it never loops. Nothing to download, and no two nights sound the same.
- You can layer up to four sounds at once and save the result as a mix, so a bed you like is one tap the next night.
- A distance control puts it Far, Near or Close, which changes how present it feels rather than just how loud it is. 42 of the 63 sounds carry it.
- It fades with the sleep timer, and the good-night screen dims itself to near black after twenty seconds so the phone stops being a light source.
What to put underneath it
Four sounds at a time is the limit, and three is usually the sweet spot. These are the pairings that hold up.
- Brown noiseCover both ends of the spectrum at once. The brown fills the low end that white barely touches, so you can drop the overall volume and still mask more.
- RainfallRain gives the hiss some irregularity. A flat noise is easy to notice precisely because it never changes, and rain breaks that up without adding anything you can track.
- FanA fan is already broadband, so it sits under white noise without fighting it, and the faint blade rhythm gives the pair a shape rather than a wall.
Questions people ask
Is it safe to play white noise all night?
The usual advice is to keep any all-night sound at a moderate level and to put the speaker across the room rather than beside your head. Tock lets you set the distance to Far, which filters the sound as well as lowering it. If you have any concern about your hearing or your child's, ask a clinician rather than an app.
White noise or brown noise?
Match the noise to the problem. If what wakes you is high and sharp, white covers it. If what wakes you is low and constant, like traffic or a bass line through the floor, brown does the same job at a lower volume because it lives in the same range as the intrusion. Most people who start on white and stay on it are covering something sharp.
Will white noise block my neighbour's TV?
Partly. Walls already absorb the high frequencies, so what reaches you is mostly the low end and the rhythm of speech. White noise has relatively little energy down there, so it has to be uncomfortably loud to cover it. Brown noise is the better tool for that specific job, and a layer of both is better still.
Does Tock's white noise loop?
No. It is generated on your phone sample by sample, so there is no file and no seam. That is true of 41 of the 63 fall-asleep sounds. The other 22 are real recordings, used where a recording genuinely beats a synthesis.
Related sounds
Nearby textures worth trying on a night this one does not land.
- Pink noisePink noise drops about 3 dB with every octave, which works out to equal energy in every octave and is close to how a lot of natural sound is distributed, from rain to wind in trees to tyres on a wet road. It reads as a balanced hush rather than a hiss or a rumble, which is why it is usually the right thing to try before you commit to either extreme.
- Brown noiseBrown noise puts almost all of its energy in the low end, dropping roughly 6 dB with every octave you climb, so it reads as a rumble or distant surf rather than a hiss. That low weight is exactly why it covers traffic, footsteps and a neighbour's bass better than white noise does, and also why it can feel like pressure if your room is already quiet.
- FanA fan makes broadband noise from air turbulence plus a very quiet periodic thump from the blades, sitting somewhere between pink and brown in balance, which is why so many people sleep to one without ever calling it white noise. Tock uses a recording of an actual fan rather than generating it, because that blade rhythm is the thing that makes it read as a fan at all.
- RainfallSteady rainfall spreads its energy fairly evenly across the audible range, close enough to pink noise that it masks about as well while sounding a great deal less like a machine. The bigger variable is the surface: rain on canvas, on glass and on a car roof are three genuinely different sounds, and only one of them will suit your room.
Elsewhere on the site
A different corner of the same problem.
- NapsThe 20 minute napA 20 minute nap is the standard recommendation because it produces a solid alertness benefit while ending before most people reach slow wave sleep, so you wake up clear rather than groggy. It is long enough to be worth the time and short enough to stay safe.
- Wake tonesSunrise alarmA sunrise alarm clock is a bedside lamp that brightens over roughly 20 to 30 minutes before your set time, and the light is the part you are paying for. Tock is an iPhone app with no light hardware at all, so it takes the timing half instead: a soft wake tone rung at a lighter moment inside the last 30 minutes rather than at a fixed time.
- Head to headAutoSleep vs Sleep CycleIf you already wear an Apple Watch to bed, AutoSleep reads a night that Sleep Cycle can only estimate from the room. If you don't own a Watch and don't want one, Sleep Cycle is the only one of the two that works, and it's your alarm as well.
- FeaturesSleep coachThe sleep coach is a chat tab inside Tock that reads your recent nights before it answers. It can quote your score, play back a clip Tock recorded, and navigate the app to change a setting on your behalf. It needs a network connection.
- Tock for youPeople who hate morningsThe alarm goes off and you feel physically wrong. Not tired exactly, more like you were pulled out of something, and it takes the better part of an hour before you are a person again.
- AlternativesTock vs Headspace SleepHeadspace Sleep is the better choice if you want a voice walking you through a wind-down inside a proper course structure. Tock is the choice if you want the night measured from the phone and an alarm that moves into a lighter moment. Neither one covers the other.
You cannot just decide to fall asleep
White noise is one of 63 sounds in Tock. Layer four at a time, save the mix, and let the alarm wake you at a lighter moment in the morning.