How loud should a white noise machine be?

Short answer: set it to the quietest level at which the noise you are trying to cover stops drawing your attention - and no higher. For an adult, that is typically a conversational background level, not a shower-running level. In a nursery the answer is stricter and the machine should be across the room rather than in the crib, because the clinical concern there is sound pressure measured at the baby’s ear.

Almost every machine on the market goes far louder than anyone should use, because a loud maximum is easy to advertise and the real skill is at the bottom of the dial. That is the whole argument of this page: a sound machine is the one piece of sleep gear where the useful specification is how finely it can be set quietly, not how much volume it has. Everything else about picking one is on the sound machine hub.

The principle: masking is about the gap, not the level

Masking works because a sound that is continuous and featureless stops your attention snagging on an intermittent one. What matters is the gap between the intrusive sound and the background, not the absolute level of either. If a snore is a little above the noise floor, you only need to raise the floor a little.

This is why turning it up usually makes things worse rather than better. You end up with a loud room, you have added a second sound to sleep through, and the snore is still intermittent above it. Research on how sleep responds to noise - Dang-Vu and colleagues on brain rhythms predicting sleep stability in noise - points the same way: what disturbs sleep is not simply how loud a room is.

It is also why the quietest machine settings get used most in practice. If you are fighting genuinely loud noise, more volume is the wrong lever - the honest options are blocking it at the ear or reducing it at the source, which machines against earplugs and the noisy neighbors page both go through.

How to set it in four minutes, without a meter

• Put the machine between you and the noise if you can, not on the far side of the bed. Placement buys you several decibels of effective masking for free.
• Start at zero and come up slowly while the noise you care about is actually happening. The right level is the first one where the intrusion stops pulling your attention - not the level where you cannot hear it at all.
• Lie down before you commit. A machine set while you are standing is set at the wrong height; sound level falls off quickly with distance.
• Check it with the phone app you already have. A phone sound meter is not calibrated and we would not publish a number from one. It is perfectly good for a relative check: is this the same as a normal conversation, or louder?
• Leave it there for a week. The instinct to nudge it up each night is habituation, not the machine losing effectiveness.

Babies: a different rule, and a stricter one

This section is not a softer version of the one above; it is a separate standard. Children’s Hospital of Philadelphia’s commentary on infant sleep machines discusses research that measured the output of commercially sold machines and found that, at maximum volume and at close range, they could produce sound pressure levels high enough to be a concern for an infant ear.

The practical rules that follow are simple and worth following exactly:

• Across the room, never in or on the crib. Distance is the single biggest variable, and it is free.
• Low volume, not maximum. The concerning measurements in that reporting are at maximum output.
• Use a timer if the machine has one rather than running it at volume all night.
• Never put a machine, a phone or a speaker inside the sleep space.

If you want a machine for a nursery specifically, the ones with genuinely usable low settings and a night light are covered on sound machines with a night light, and the broader question of whether these devices are harmful is on are white noise machines bad for you.

Should it run all night, or time out?

Both are defensible and they answer different problems. If the noise you are masking only happens at bedtime - a street that goes quiet by midnight, a housemate watching TV - a 30 or 60 minute timer gives you the benefit and then stops adding exposure. If the problem is a partner who snores from 1am or a neighbor on a night shift, timing out means waking up when it stops.

The thing to avoid is the middle: a machine running all night at a volume chosen for the loudest moment of the evening. If you need all-night masking, set the level for the quiet hours and accept that the loud moments will come through a little.

Machine type matters here too. A mechanical fan machine such as the Dohm produces genuinely non-repeating sound with no loop to notice, which is easier to leave on for eight hours; digital machines vary, and on quiet settings a short loop becomes audible as a seam. That trade-off is the subject of machines against an ordinary fan and the noise colors explainer.

The exposure question, for adults

A machine on a nightstand at a conversational level is not a hearing risk, and we are not going to pretend otherwise. The reason volume still deserves thought is duration: the WHO’s safe listening framing is built around level and time together, and the WHO night noise guidelines treat sustained nighttime sound as something worth reducing rather than adding to.

The practical reading is the same advice as the top of this page, which is why we are comfortable giving it plainly: use the least volume that works, put distance between you and the machine rather than turning it up, and if you need a lot of level to get anywhere, the problem is not the machine’s volume - it is that you are using a masking tool against a blocking problem. Anything played in your ears all night is a stricter version of the same arithmetic, which is covered on whether it is bad to sleep with headphones on.