White noise is the simplest of the three noise colors here: equal energy at every frequency at once, the audio version of white light. Nothing is weighted toward any pitch, which gives it that flat, familiar hiss — an old fan, an air conditioner, a radio tuned between stations.
Why people reach for it first
It's often the first sound people try, because most of us already have a memory of something like it. Because it covers the whole range evenly, it's also good at masking a wider mix of other sounds — a hum in one register, a voice in another. Green and brown noise shape that even spread into something rounder; try them side by side and see which one you'd rather have running. Whichever you pick, it plays for as long as you choose and fades out on its own.
Listen safely
This is a sound, played back through whatever speaker or headphones you already own. It doesn't diagnose, measure, or promise anything about how you sleep, focus, or feel — it's just noise and a handful of real recordings, mixed the way you like them.
Keep the volume low enough that you'd still notice a smoke alarm, a phone ringing, or someone at the door. If you fall asleep in headphones, choose a volume and a pair you'd be comfortable wearing all night, and a session length that ends when you'd want the sound to stop.
If you use this near a baby, keep the speaker several feet from the crib, never inside or clipped to it, and keep the volume low — the same care you'd take with any sound machine in a nursery.
If your relationship with sound, or with sleep, feels difficult rather than simply restless, a doctor or audiologist is the right person to talk to. This is a mixer, not a clinician.
What exactly is white noise?
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It's a signal that carries equal energy at every frequency across the range you can hear, the audio equivalent of white light containing every visible color at once. That even spread is what gives it its flat, bright, hissy character, compared with green or brown noise, which weight their energy toward the middle or the low end instead.
Why does white noise sound brighter or harsher than green or brown noise?
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Human hearing is more sensitive to some frequencies than others, and white noise's energy is spread evenly rather than shaped to match that sensitivity. The result is a sound that reads as thinner and brighter than green or brown noise, even though all three are built the same basic way, just with different weighting.
Is this the same white noise as an old television or radio between stations?
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It's in the same family, though a real, unshielded analog radio or television picking up static was never a perfectly even spread of frequencies — that was a mix of white noise and whatever interference the device itself picked up. What plays here is generated cleanly and directly, without any of that hardware in between.
Does white noise mask other sounds better than brown or green noise?
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Because it covers the full range evenly, white noise can be effective at covering a wide variety of other sounds, from a hum in one register to a voice in another. Whether that's what you want, or whether you'd rather have the gentler, more weighted character of green or brown noise, is a matter of preference.
How loud should it be?
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Loud enough to notice, quiet enough that you could still hear someone talking to you from across the room without straining.