Misconceptions
What most treatment gets wrong.
Most of what is marketed for room acoustics only works on certain frequencies, and not the ones causing the problem.Four things worth knowing before you make a decision.
Keeping sound out of a room and controlling it inside are two different builds.
Thin panels work on short wavelengths. The bass passes straight through them and back into the room.
The rating most products quote leaves out the bass frequencies where most room problems begin.
Treating only part of the range leaves a room lifeless.Dry is the goal, dead is not.
Soundproofing vs acoustic treatment
Soundproofing is not acoustic treatment.
The two get used interchangeably, and they are not the same thing.Different problems, solved by different builds, at different points in a project.
Keeping sound out
Soundproofing
- Stops sound crossing a wall, a floor, or a ceiling.
- Works by mass, sealing, and separating structures.
- Decided at construction, and expensive and impractical to add later.
- Does nothing for how sound behaves inside the room.
Controlling sound inside · what we do
Acoustic treatment
- Changes what a sound does after it leaves the speaker.
- Works by absorption and diffusion, placed where the room is causing the problem.
- Can be done to a room that is already finished.
A room can be perfectly isolated and still sound wrong inside.
What to do instead
Work out which problem you have first. If the complaint is the neighbours, that is isolation. If the complaint is what you hear in the room, that is treatment. Buying one when you needed the other is the most expensive mistake in this category.
Foam
Foam fixes the wrong problem.
It is the cheapest thing that looks like treatment,which is why it is everywhere.
The assumption
What actually happens
Cover the walls in foam and the room is treated.
Standard foam runs 25 to 50 mm.A panel can only act on wavelengths it is thick enough to meet, so a thin one works at the top of the range and passes everything long straight through.
Taking the harshness off makes the room sound better.
The top comes off and the buildup underneath stays exactly where it was.You end up with a room that is dull and boomy at the same time.
More foam means the room is balanced.
Adding more of a material that never reached the low end only takes out more of the range it was already taking.The room ends up dead and lifeless.
What to do instead
Judge treatment by depth before anything else. How depth works →
NRC
A good NRC rating says nothing about bass.
It is the figure printed on most products sold as acoustic treatment,and it is the most misread number in the category.
NRC is an average of how much sound a material absorbs at four frequencies: 250 Hz, 500 Hz, 1 kHz and 2 kHz. The result is rounded to the nearest 0.05.
The bass is not in it. Nothing below 250 Hz is measured, reported, or reflected in the score, and that is where most room problems begin.
So a product can carry a high rating and still do nothing at all in the range you are trying to fix.
What to do instead
Ask for absorption plotted across the frequency range rather than a single averaged figure, and treat a before-and-after measurement in your own room as worth more than any lab number on a datasheet.
Dead vs dry
A dead room is not a treated room.
It is what most people picture when they think of acoustic treatment,and it is the opposite of what a treated room should sound like.
The assumption
What actually happens
Covering the whole room with foam will fix the problem.
The issue is not how much absorption. It is the wrong absorption, everywhere.Thin material on every surface takes the top off the entire room and leaves the low end exactly where it was.
A room that sounds dead is the goal.
That is a dead room, one where only the highs were treated.It is what most people imagine treatment does, and it is why treatment has a reputation for sucking the life out of a space.
The fix is to take some of it back down.
The fix is treating the whole range instead of the easy part of it.Dead rooms are uncomfortable to be in.Dry rooms are accurate,and let your speakers do what they were built to do.
What to do instead
Treat across the full range rather than the part that is cheapest to reach. Dry is the target: controlled and accurate, and still a room you want to spend time in. Sink and Scatter →
Not sure which of these you have?
Tell us what the room is for, send the dimensions and a few photos, and we will come back with an honest read on what it is actually doing.