All 32 sounds
Recordings come from licensed sound libraries, cut and levelled for sleep, and played so they never loop audibly. Noise colors and tones are generated on your phone. 8 are free; Premium unlocks the rest.
Noise colors
Generated on your phone, steady from the first second to the last. 7 sounds
White NoiseEqual energy across the whole range. Bright and even, the classic choice for covering voices and street noise. 
Pink NoiseSofter than white: the high end is turned down, so it sounds more like steady rain than static. 
Brown NoiseMost of the energy sits low. A deep, rounded rumble with almost no hiss. 
Deep BrownBrown noise with everything above about 200 Hz filtered away. Felt as much as heard. 
Green NoiseNoise centred on the middle of the range, around 1 kHz. Fuller than white, lighter than brown. 
Blue NoiseOnly the highs, above about 4 kHz. Airy and crisp, best at a low volume or in a mix. 
Violet NoiseThe very top of the range, above 6 kHz. A thin, fine hiss. Few people use it alone; it can add air to a mix at low volume.
Nature
Field recordings from licensed sound libraries. 11 sounds
RainA real recording of heavy, steady rain. Turn the tone down for rain heard from indoors. 
Ocean WavesSurf breaking close on a beach, recorded on the coast. Slow swells, no seagulls. 
CricketsA summer meadow at night. Crickets close by and a wide, quiet field behind them. 
ThunderRecorded rain with thunder at random moments. Every strike fades in, never cracks; set how often and how far away. 
RiverA mountain stream recorded close up. Constant, bubbling water. 
Forest BirdsA countryside dawn chorus. Better for waking slowly or reading than for the middle of the night. 
WindDesert wind, a soft rushing that rises and falls. 
FrogsFrogs and insects in a rice field in South India, at night. 
Rain on TentRain drumming on a tent, recorded from inside. Close, soft and steady. 
Rain on RoofSteady rain on a shed roof. Even and dense, with no thunder. 
CicadasCrickets and cicadas on a warm summer day. A bright, shimmering texture.
Home & travel
The machines and places people fall asleep to. 9 sounds
FanA real bedroom fan. The sound many people already sleep with, without the draft. 
FireplaceA small wood fire, crackling gently. 
WasherA washing machine in its slow wash cycle. Low, rhythmic sloshing. 
DryerA tumble dryer turning. Warm, even drone. 
AirplaneInside a Boeing 757 cabin at cruise. The engine hum that sends half the plane to sleep. 
TrainA passenger car of Chicago's L train in motion. Rails, rattle and sway. 
Cat PurringA Norwegian Forest Cat purring up close. 
ShowerA running shower. Warm, even water noise. 
Air ConditionerAn air conditioner's fan humming. A low, steady drone.
Calm & rhythm
Slow, simple sounds for winding down. 5 sounds
HeartbeatA heartbeat recorded through a stethoscope. Set the pace anywhere from 40 to 100 beats per minute. 
LullabyBrahms' lullaby on a music box, recorded live. 
ShushSoft shushing that swells and settles. Choose a slow or quicker rhythm. 
432 HzA pure, steady 432 Hz tone. Some people like a single tone under other sounds. We make no health claims for it. 
528 HzA pure, steady 528 Hz tone, slightly brighter than 432 Hz. No health claims, just a tone.
Where the recordings come from
The nature and home recordings are licensed from the Sonniss GDC Game Audio Bundles and from Freesound (CC0). We cut a long, clean stretch from each, level them to a similar loudness so nothing jumps out when you switch, and let the app pick random segments as it plays. Thunder strikes are separate recordings mixed over rain, each with a slow fade-in.