Wooden acoustic panels: how they work and where to put them Absorbing or diffusing sound, where to put them and how many you need
In a room you don't only hear the speakers: you hear the walls too. Acoustic panels keep the sound bouncing off them under control. Here is how they work, where they go and when they're enough.
Sound bounces.
When a speaker plays, the sound doesn't only travel straight to your ears. Part of it hits the side walls, the ceiling, the floor and the wall behind you, and comes back with a small delay. These are reflections.
The first reflections, from the nearest walls, arrive a few milliseconds after the direct sound. The ear doesn't hear them as an echo: it blends them into the sound. Voices lose their outline, instruments don't stay in place and the treble turns harsh. In rooms with bare walls, large windows and smooth floors the problem is more obvious.
Absorb or diffuse.
An absorbing panel is made of a soft, porous material, such as rock wool or polyester fibre. It soaks up part of the sound's energy, so the reflection comes back weaker.
A diffusing panel, on the other hand, has an irregular surface, with blocks or slats at different depths. It doesn't take energy out of the room: it sends it back in many directions and slightly staggered in time, instead of all at once towards you. The reflection is still there, but it arrives scattered and doesn't get in the way.
The two aren't competing. Absorption is for when the room booms and is full of echo; diffusion tidies up the reflections without deadening the room. If you absorb too much, the room goes dead and the music loses its air: it's the most common mistake.
My panels. Skyline, Pyramid, SoundWave and Wave are panels that diffuse sound: wooden blocks and slats at different depths. They correct the room and decorate the wall at the same time.
Where to put them: the mirror trick.
The place to start is the first reflections on the side walls. To find them you only need a mirror and a helper:
- Sit in your listening position.
- Ask someone to slide a mirror along the side wall, at the height of your ears, between you and the speaker.
- When you can see the speaker in the mirror, that's the first reflection point: mark it with a piece of tape.
- Repeat with the other speaker and on the other wall.
The same trick works on the ceiling and on a desktop. That's where the first panel goes.
The other walls.
Behind the speakers. The wall behind the speakers receives the sound coming from the sides and back of the speakers. A diffusing panel here widens the soundstage and becomes a backdrop for the system.
Behind you. The back wall sends sound to your ears from behind. In a small room, with the sofa close to the wall, this is where diffusion makes the biggest difference.
Corners and bass. Bass builds up in the corners and makes the room boom. No thin panel stops it: for that you need thick bass traps in the corners, or to move the speakers and the sofa a little. I cover this in the guide on how to position your speakers.
How many you need.
Fewer than you think. Start with the first reflection points, listen for a few days, then add the wall behind the speakers or the one behind you. There's no need to cover the walls: a few panels in the right places count for more than lots of panels placed at random.
A simple test: clap your hands loudly in the middle of the room. If you hear a metallic echo ringing between two parallel walls, those walls need a panel. Repeat the test once it's up.
Mistakes to avoid.
- Deadening everything. Too many absorbing panels make the sound flat and lifeless.
- Sitting right next to a diffusing panel. It needs a little space to work: as a rule, sit at least six times its depth away from it.
- Expecting it to fix the bass. For that, the corners and the position of the speakers and sofa are what count.
- Treating only one side. The room should stay symmetrical: whatever you put on the left also goes on the right.
I also build every panel made to measure, in the wood and size your wall needs.
Acoustic panels on ExtrasoundMy wooden panels are sold on Extrasound, the hi-fi shop that sells them.
Frequently asked questions.
What is the difference between absorbing panels and panels that diffuse sound?
Absorbing panels soak up part of the sound, so the reflection comes back weaker. Diffusing panels send it back in many directions: the reflection is still there, but scattered. The first fight echo, the second tidy up the sound without deadening the room.
Where do acoustic panels go in a living room?
First on the first reflection points of the side walls, which you find with a mirror from the listening position. Then on the wall behind the speakers or the one behind the sofa.
Do wooden panels help with bass too?
No. Wooden panels work on the mids and treble. Bass is corrected with thick traps in the corners and by moving the speakers and the sofa.
How many acoustic panels do I need?
A few, in the right places. Start with the first side reflections and add more only if needed: too many absorbing panels make the room dead.
Do acoustic panels soundproof against the neighbours?
No. They correct the sound inside the room. To avoid disturbing the neighbours you need soundproofing, which means work on the walls themselves.