Sleep Lab · Sound & sleep · 5 min read
White noise, brown noise, or just a fan?
The choice is not about which colour of noise works best. It is about which sound your room is missing — and whether you are trying to cover a sudden noise or a constant one.
Where do you start — the complaint or the category?
The question is usually asked as a ranking — which of the three is best. That framing is the problem. A door closing, a car passing and a floorboard cooling down are sudden sounds with edges. A fridge, distant traffic or an air conditioner are low sounds that are already there all night. They are not the same complaint, so they do not have the same answer. Name the sound that wakes you first; the rest of this page is a way to match it.
What jobs do the three sounds do?
White noise spreads its energy evenly across the frequencies we can hear, which is why it reads as a bright, steady hiss. That evenness is the useful part: it gives a sudden sound fewer edges to stand out against, so the door and the passing car arrive into something rather than into silence.
Brown noise carries more of its energy in the low frequencies and much less up high. It reads as deeper and further away — closer to a distant rumble than to a hiss. If what you are covering is already a low, constant sound, adding a bright layer on top of it can be more noticeable than the sound you started with.
A fan is not a recording of anything. It is a real machine in the room, with a motor, a blade and moving air. That last part matters in a way the other two cannot match: it changes the air as well as the sound. It also means a fan has its own constraints — it is sitting in the room, it has a direction, and in a cold month you may not want the airflow at all.
The names describe how the sound is distributed. They are not claims about what it does to you. Nothing on this page says any of the three helps you sleep, and we are not going to imply it.
Why is the loop the thing to check?
Whichever one you choose, listen for the seam. A short recording played on repeat gives you something to wait for: the point where it starts again. We have said the same thing elsewhere on this site — a loop can be worse than nothing, because your attention goes to the join instead of settling. A real fan has no loop at all, because there is no recording to repeat. If you use a track, choose one long enough that you never hear it begin twice.
What are we not going to claim?
We do not print decibel figures, frequency ranges or running times here. Our own devices do not have written specifications with us yet, and a number we cannot stand behind is worth less than none. We are also not quoting research or customer comments on this page. The English material we found on this topic was either a page selling a machine or an article repeating confident percentages without a single first-hand source, and we could not verify an original post. So there are no quotes, no figures and no product names below.
There is nothing to buy from this page either. We make things for the hour before bed, but we will not name an unshipped product in a comparison it has no part in. This is a question about where a sound sits in a room, not about which device to order.
How do you decide tonight?
- Name the sound. Write down what actually wakes you. If it is sudden, start with the broadest, most even sound you have. If it is a low, constant rumble, start with less hiss.
- Listen for the join. Give it ten minutes. If you catch yourself waiting for the track to come round again, change the sound before you change anything else.
- Change one thing. Keep the volume and the position the same and change only the sound. Two variables changed at once tells you nothing.
- Keep it low. Set it quiet enough that you would still hear a voice in the room. A sound you stop noticing has done its job.
About AERÉ
AERÉ is a sleep and everyday-wellness home brand based in Hangzhou, China, designing twenty things for the hour before bed.
Questions people ask next
Neither is better in general. One spreads its energy evenly and reads bright, the other sits lower and reads further away. Which one helps depends on the sound you are trying to cover, not on a ranking.
They are different objects. A fan has no loop and it moves the air; it also has a motor in the room and airflow you may not want in winter. Decide which of those you actually need before comparing them.
We do not print a decibel figure here. Keep it low enough that you would still hear a voice in the room, and change only one thing per night so you can tell what made the difference.