How to Block Out Traffic Noise at Night
Short answer
To block out traffic noise at night, first seal gaps around windows, doors and vents. Then play brown noise all night through a speaker near your bed. Your walls already block the high sounds, so traffic indoors is a low rumble that brown noise covers. White noise mostly adds hiss. Covering the noise does not reduce what reaches you.
What Reaches Your Bedroom Is Not What Is Happening Outside
Stand in the street and traffic is a broad, bright sound: engine, exhaust, tyres on the road, the hiss of air. Lie in bed with the window shut and it has become a rumble. Nothing changed outside. The building did it.
Walls, glass and floors block high sounds and let deep sounds through. High sounds lose energy easily as they pass through solid material. Deep sounds carry through a building much better and arrive almost whole. So a building removes the top of a sound and lets the bottom past. This is why you hear your neighbour's bass line and not the tune, and why traffic indoors is a rumble, not a hiss.
That one fact settles which colour to use. Whatever the traffic sounds like in the street, what reaches your bedroom is mostly deep sound. Sound masking means covering one sound with a steadier one, so your brain stops noticing it. It only works when the covering sound is in the same range as the noise. So you want the sound with most of its energy in the deep range: brown noise. White noise puts most of its sound far above where the traffic now is. That is why people try it against traffic, find it does nothing, turn it up, and end up with hiss on top of a rumble.
It also explains a common mix-up. Advice written for offices recommends white noise, and it is right there, because the problem in an office is speech. Advice for a bedroom near a road should not say the same thing, but a lot of it does.
Two Different Noises Are Both Called Traffic
Knowing which one you have tells you how much masking can really do. It is worth finding out before you spend anything.
Engine and exhaust noise is loudest at low speeds. Pulling away from a junction, a slow residential street, a bus. It is the deepest part of traffic noise, and it gets through a building better than anything else. It is also the part brown noise covers best.
Tyre noise takes over above town speeds. Somewhere around thirty to fifty kilometres an hour, depending on the vehicle and the road surface, the sound of rubber on the road becomes the bigger part. It has more high sound than engine noise, but by the time it has come through your window, the high part has gone anyway.
Distance turns separate cars into a hum, and that is the easy case. A motorway several hundred metres away makes a steady low drone with no single vehicles in it. Steady sound is the ideal thing to cover, because the covering sound only has to sit above a level that never changes. So a modest volume handles it and keeps working all night. If this is your situation, masking will work well.
A road under your window is the hard case. At night, a quiet street with the odd car is not a hum but a series of separate events. Each one rises out of near-silence and falls back. Masking handles that poorly. Covering the peak means playing the sound far louder than the rest of the night needs, and sudden sounds are exactly what hearing is built to notice. It still helps. It helps less, and it is better to know that in advance than to decide it failed.
Masking Helps You Cope, but Does Not Lower the Noise
This section exists because most pages on this subject leave it out, and it changes what you should do.
Masking does not reduce what reaches you. It raises the background so the traffic stops standing out. The traffic arrives exactly as before, and the total sound in the room goes up, not down, because you added a sound. That is a fine trade if the aim is to stop being woken. It is not the same as being in a quieter room.
Night-time noise can affect your body even if you do not wake up. This is why noise limits exist at all: the effect is measured in the body, not in whether you remember anything in the morning. The World Health Organization's Environmental Noise Guidelines for the European Region strongly recommend keeping road traffic noise below 53 decibels averaged across the day, evening and night, and below 45 decibels at night, to protect sleep.
What to do with that. If you are well above those levels (and living beside a busy road usually means you are), masking is worth doing tonight, but it is not the whole answer. The steps in the next section reduce what actually reaches you, and they are what change your exposure. Many countries also let you report road noise to a local authority, and have noise maps that show what your address is exposed to. Do both: fix what you can, and cover what is left.
Fix the Gaps First: It Costs Less Than Anything Else Here
Sound behaves like water in one useful way: it takes the easiest path, and one small opening undoes a lot of solid building. In most bedrooms the weak point is not the wall or even the glass. It is a gap.
Find where air gets in. A small vent in the window frame, a letterbox, a gap under the door, an unsealed extractor fan, worn draught seals, a keyhole, cables coming through a wall. If air moves through it, so does sound, and no amount of solid wall elsewhere makes up for it. This gives the most benefit per pound of anything on this subject, and it usually takes a weekend and the cost of some seals.
Check that the window closes properly. Older hinged and sash windows often no longer seal along their whole length. A window that is shut but leaking along one edge blocks far less than its glass suggests.
Secondary glazing usually beats new double glazing for noise. This surprises people. A sealed double-glazed unit has a narrow gap between the panes, sized to keep heat in. The two panes are close enough that, for sound, they act a bit like one. Secondary glazing is a separate inside window with a wide air gap and no solid link to the first. It blocks sound much better, and it is often cheaper than replacing the original window. If you are spending money on noise, spend it here, not on new units.
Heavy curtains do less than you hope. A thick curtain soaks up some of the high and middle sounds, which your wall already removed. Against the low rumble that actually reaches you, it does very little. Curtains are not useless, but they are not the answer.
Move the bed, or move the room. If there is a quieter side of the home, the cheapest fix of all is to sleep on it. Putting the head of the bed on the wall furthest from the road, and a wardrobe against the road-facing wall, is free and does more than most purchases.
Setting the Masking Up
Brown noise, through something that can play it. Most of brown noise is deep sound, which is the point, and a phone speaker cannot play it. Through a phone you get the thin top and none of the useful part. Use the player above with headphones to check the colour is right. Then run it overnight on a speaker with real bass, or a sound machine of a decent size.
Set the volume against a passing vehicle, not against the quiet gaps. Wait for a lorry, or the loudest thing your road often produces, and set the volume so that it stops standing out. A volume chosen during a quiet minute will be too low for every vehicle that follows.
Put the sound near you, not near the window. The natural urge is to put the speaker at the source of the problem. Masking does not work that way. The covering happens at your ear, so what matters is the volume there. A speaker close to the bed does the same job at a much lower volume. That means less sound in the room and less spilling into the rest of the house.
Run it all night. A timer that ends at two in the morning hands the room back to the road at the worst possible time. Note that a browser tab cannot do this. Every website, this one included, is paused by your phone or computer when the screen locks. The generator here is for testing whether the colour is right, which takes five minutes. For the whole night, you need an installed app or a sound machine.
If brown does not quite cover it, try pink. Some rooms (a thin single-glazed window, a road very close) let more of the high sound through than usual. Pink noise reaches higher, while still having plenty of deep sound. The buttons on the player above switch between them.
What This Will Not Do
It will not help much with sudden one-off sounds. A motorbike at one in the morning, a slammed car door, a siren. These rise far above any sensible masking volume, and they are the sounds hearing is most alert to. Steady masking softens the edge but does not remove them.
It will not reduce your exposure, which is covered above and is the reason the section on gaps and glazing comes before this one.
It will not fix vibration. Heavy vehicles on a poor road surface can shake a building, so you feel the noise as much as hear it. Sound masking cannot help with that. The fix is in the building, not the air.
It is not a treatment for insomnia. If your sleep has been poor for weeks, and a quieter road does not change that, the next step is a clinician, not a different colour of noise.
If You Only Read One Paragraph
Your walls and windows already removed the high sounds from the traffic outside, so what reaches your bed is a low rumble. That is why brown noise covers it and white noise does not, whatever office advice says. Before you cover anything, find and seal the gaps where air gets in, because one gap undoes a lot of solid wall and it is the cheapest fix. If you spend money on glazing, secondary glazing with a wide air gap beats a new sealed unit for noise. Then play brown noise on a speaker that can really play deep sounds. Set it against a passing vehicle, not a quiet minute. Place it near your head, not near the window, and run it all night, not on a timer. A distant motorway is easy to cover. A quiet street with the odd car is much harder, because masking handles sudden sounds far worse than a steady hum.
Frequently Asked Questions
What noise is best for blocking traffic?
Brown noise. Traffic outside has every kind of sound in it, from deep to high. But walls and glass block the high sounds and let the deep ones through, so what reaches a bedroom arrives as a rumble. Masking only works when the covering sound and the noise are in the same range, so the sound with most of its energy in the deep range is the match. White noise puts most of its sound far above where the traffic now is, which is why it seems to do nothing against a road.
Why does white noise not block traffic noise?
Because it is aimed at the wrong range. White noise spreads its energy evenly from deep to high, so most of what it makes is higher than the traffic that got through your window. Only the small part that overlaps does any covering. So you turn it up, and what you mostly add is hiss. Advice that recommends white noise is usually written for offices, where the problem is speech, not a road.
Does sound masking reduce the health effects of traffic noise?
No, and it is worth being clear about this. Masking raises the background so the traffic stops standing out. The traffic still arrives, and the total sound in the room goes up because you added a sound. Night-time noise can affect your body even if you do not wake up or remember anything. That is why the World Health Organization recommends keeping road traffic noise below 53 decibels averaged over the day, evening and night, and below 45 decibels at night. Masking makes the night more bearable. Sealing gaps and better glazing are what lower your exposure.
What is the cheapest way to reduce traffic noise in a bedroom?
Sealing the gaps where air gets in, by far. Sound takes the easiest route, and one small opening undoes a lot of solid building: a small window vent, a gap under the door, worn window seals, a letterbox, an unsealed extractor fan, cables through a wall. Some draught seals and an afternoon will usually do more than anything you can buy. After that, moving the head of the bed to the wall furthest from the road is free.
Is double glazing or secondary glazing better for noise?
Secondary glazing is usually better for noise, which surprises people. A sealed double-glazed unit has a narrow gap sized to keep heat in, and the two panes sit close enough together that, for sound, they act a bit like one. Secondary glazing is a separate inside window with a wide air gap and no solid link between the panes. It blocks sound far better, and it is often cheaper than replacing the original window.
Do curtains block traffic noise?
Barely, against traffic. A heavy curtain soaks up some middle and high sounds, and those are exactly the sounds your wall and window already removed. What still reaches you is a low rumble, and a curtain does very little against that. Curtains are not useless in a room, but if the problem is a road, do not spend your money there.
Where should I put the speaker to mask traffic?
Near your head, not near the window. The natural urge is to put it at the source of the problem, but masking happens at your ear, not at the wall. What matters is the volume where you are listening. A speaker close to the bed does the same job at a much lower volume. That means less sound in the room and less of it reaching the rest of the house.
Does masking work better for a motorway or a residential street?
A motorway, clearly. Distance blends single vehicles into a steady drone, and steady sound is the ideal thing to cover. The covering sound only has to sit above a level that never changes, so a modest volume works all night. A quiet residential street makes separate events instead, each rising out of near-silence. Covering the peaks means playing the sound far louder than the rest of the night needs. Masking still helps there; it just helps less.