Window furnishings can take the edge off outside noise, but they don’t soundproof a window. The honest version is that a well-fitted blind adds mass and breaks up the sound bouncing around a hard room, which makes traffic, barking and mowers less sharp. It won’t stop the deep rumble of a truck, because that’s low frequency and it travels straight through glass.
What makes the difference isn’t the brand on the blind. It’s three things: how much material sits between you and the glass, how completely it covers the opening, and whether you’ve closed the gaps at the top and sides. Get those right and the room is noticeably calmer. Get them wrong and the best blind in the catalogue does very little.
Through the window, almost always. A brick or clad wall is heavy and stops sound well. Glass is thin, light and rigid, so sound makes it vibrate and the vibration carries into the room. The window is the weak point in the wall.
There are two paths, and they behave differently.
Airborne sound through gaps. Sound follows air. A gap around a sash, a worn seal or a window left ajar lets noise straight in. Guidance from BRANZ on noise control in the building envelope makes the point bluntly: when a window is open, any sound rating it had is lost. Gaps matter more than materials.
Vibration through the glass. Even a sealed window transmits sound, because the pane itself moves. Heavier and thicker glass does this less, which is why laminated and double glazing work. A blind can’t change the glass.
There’s also frequency. High-pitched sound, such as voices, birds, brakes and mower whine, is easy to absorb and block. Low-frequency sound, such as truck rumble, bass from a party or a distant freeway, passes through light materials as though they weren’t there. That’s why window furnishings help with some noise and barely touch other noise, and it’s worth knowing which kind yours is before you spend money.
Three useful things, and one they can’t do.
They add a layer of mass. A closed timber venetian or a heavy roller fabric puts a second surface in the sound path. Not much mass compared with glass, but it’s not nothing, and it works best on the higher frequencies that make noise feel intrusive.
They trap a pocket of air. The space between the blind and the glass behaves a little like the cavity in double glazing. It’s why a well-fitted blind with the gaps closed outperforms the same blind hanging loose in front of the window.
They cut reverberation in the room. This is the effect people notice. A room with bare glass, hard floors and no soft surfaces makes every sound bounce and sharpen. Cover the glass and the same noise sounds duller and further away, even though the amount of sound entering has hardly changed.
They can’t block low-frequency noise. No blind, curtain or shutter will stop a truck on a hill or the bass from next door. If that’s your problem, the fix is in the glazing and the seals, not the furnishings.
Treat window furnishings as part of the answer. On a busy road, the sensible order is seal the gaps first, then dress the window properly, then look at glazing if it still bothers you.
Two properties decide it: mass and the ability to absorb rather than reflect.
Timber. Dense, solid and heavier than most alternatives at the same thickness. A closed timber venetian presents a near-continuous timber surface across the opening, and the slats break up sound that would otherwise bounce straight back off the glass. Wider slats mean fewer gaps between them when closed. Our basswood and cedar venetians come in 45mm, 50mm and 63mm, and the wider options close up tighter across a large window.
PVC and faux timber. Heavier than fabric, lighter than hardwood, and it holds a closed position well. A sensible middle ground where timber isn’t suitable.
Thick fabric. Blockout roller fabric is denser than standard fabric and has a coated backing that adds a little mass. Dense weave beats loose weave every time. A sheer fabric does almost nothing acoustically.
Aluminium. The weakest of the common materials for noise. Thin, light and rigid, so it reflects sound rather than absorbing it, and slats can rattle.
Air gaps. The least obvious one and often the most effective. A layer of still air between the blind and the glass does real work. It’s also why two lighter layers usually beat one heavy layer on its own.
The simple rule: heavier, denser and more continuous is better. A heavy blind with a 40mm gap down each side will lose to a lighter blind that covers the opening properly.
This is the part most people get wrong. Sound behaves like water. A small gap undoes a large surface.
Fit the opening, not the window. An outside mount that extends past the frame covers more of the wall and leaves fewer edges for sound to flank around. An inside mount looks neater but leaves a small gap at each side by necessity, since the blind has to clear the reveal to operate.
Close the top. The gap above a blind, where the roller or headrail sits, is an open channel into the room. A pelmet across the top closes it. This is the single cheapest improvement most people can make, and it helps with heat as much as noise. Every Blinds Deal order includes a colour-coordinated pelmet, so it’s worth fitting it rather than leaving it in the box.
Mind the sides. The narrower the side gaps, the better. Measure carefully and order to the opening rather than guessing. Our measuring guide covers inside and outside mount.
Go wider and longer than the glass. On a face-fit install, extending 100mm past each side and below the sill adds coverage that costs almost nothing.
Layer where it counts. Two layers with air between them beat one layer, every time. A blind at the window with curtains over it is the most effective combination for a bedroom on a main road.
Keep it closed. Obvious, but the acoustic benefit only exists while the blind is down and shut. If noise peaks at particular times, like early traffic or a Friday night, that’s when the blind needs to be closed.
| Type | How it performs on noise | Best suited to |
| Timber venetian | Good. Dense slats, close to a solid surface when shut, wider slats close tighter | Bedrooms, living rooms, home offices on a busy street |
| PVC venetian | Moderate to good. Less mass than timber, holds a closed position well, handles damp | Bathrooms, laundries, kitchens, coastal homes |
| Blockout roller | Moderate. Coated fabric adds some mass, performs best with a pelmet and a wide fit | Bedrooms, media rooms, anywhere you want a flat clean look |
| Standard roller | Light. Helps with echo, little else | Rooms where noise is a minor annoyance |
| Vertical blind | Light. Vanes overlap rather than seal, so sound passes between them | Large windows and sliding doors where coverage matters more than acoustics |
| Blind plus curtains | Best of the practical options. Two layers with air between them | A bedroom on a main road, where sleep is the priority |
The pattern is consistent. Mass and continuous coverage win. A closed timber venetian fitted wide of the opening with a pelmet above it is doing about as much as a window furnishing can do on its own.
The rooms with the noisiest windows are often the damp ones. A bathroom window onto a side lane, a laundry that backs onto a neighbour’s driveway, a kitchen above a road. Pick a material for noise and ignore moisture in those rooms and the blind warps, swells or grows mould inside a couple of years.
PVC venetians are the straightforward answer for wet rooms. They don’t absorb water, they wipe clean, and they won’t warp above a shower or a sink. You give up some mass against timber, but a warped blind that no longer closes flat has lost far more than that.
Western red cedar is the timber option where moisture matters. Its natural oils resist water and fungal growth, which is why it suits bathrooms, laundries and kitchens better than basswood. If you want the density of timber in a damp room, cedar is the one to ask about.
Basswood belongs in bedrooms, living rooms and offices, where humidity is low. It takes paint and stain evenly and holds its shape, but it isn’t the right pick for a steamy bathroom.
Coastal homes are their own case. Salt air and high humidity are hard on everything, and condensation on single glazing runs down onto the bottom rail. PVC or cedar is the safer choice anywhere near the water.
One practical note. Condensation sitting between a closed blind and cold glass is what does the damage, and closing a blind tight for noise makes that pocket worse. Air the room daily and wipe the sill in winter, whichever material you choose.
If the noise is bad enough to wake you, window furnishings alone won’t fix it. Work in this order, cheapest first.
For road noise specifically, the South Australian Department for Infrastructure and Transport publishes a homeowner guide to reducing transport noise impacts that covers seals, glazing and secondary windows in more detail. The physics is the same in any state.
They make a real but modest difference, mostly to higher-frequency sound and to how a room echoes. Anyone promising silence from a blind is overselling it. The honest claim is a calmer room, not a soundproof one.
Timber, because it’s denser. The exception is a damp room. A PVC venetian that stays flat in a bathroom beats a timber blind that warps and no longer closes properly, and a blind that doesn’t close does nothing for noise.
Some. Wider slats mean fewer joins across the window, so a closed blind presents a more continuous surface. On a large window a 63mm slat closes up better than a 50mm. The effect is small next to fit and coverage.
Yes, more than people expect. It closes the open gap above the headrail, which is a direct path for both sound and heat. Every Blinds Deal order comes with a colour-coordinated pelmet, so fit it.
If noise is affecting your sleep, yes. Two layers with a pocket of air between them outperform any single layer. Blinds handle light and privacy; curtains add mass and absorption.
