ᐅ Reducing the Noise from a BILLY Bookcase – How Does It Work?

Hello everyone,

I recently bought a BILLY shelf from IKEA to accommodate some speakers and audio components. However, I noticed that the shelf’s material and construction reflect sound quite strongly and sometimes even amplify it—especially the back panel, which causes a reverberation time that makes the volume seem louder.

My specific question is: How can the volume or the amplification and reflections caused by the BILLY shelf be reduced as much as possible?

I am thinking of measures like insulating the back panel, avoiding hard surfaces, or adding sound absorbers, but I am not sure which solutions work well in everyday use and how to best implement them.

Does anyone have practical experience or tips to significantly improve the sound when using a BILLY shelf with speakers inside, or to reduce the perceived volume?

I look forward to your suggestions and advice!

lazaroge schrieb:
My specific question is: How can the volume and the resonances and reflections caused by the BILLY shelf be reduced as effectively as possible?

Hey,

great question! I’m quite familiar with this issue since I also have a few speakers placed inside a BILLY shelf. The good news is: there are several things you can try without tearing down the whole shelf or installing high-end acoustic panels 😉

First, using textiles often helps. For example, attaching thin felt sheets or carpet scraps to the back or sides can absorb some of the reflections and dampen the sound.

You could also consider replacing the back panel with a thin foam board or adding one behind the existing back panel. That can significantly reduce reverberation.

And very importantly: position the speakers a little bit away from the inside surfaces of the shelf, so they aren’t directly on the back panel or edges. This reduces strong immediate reflections.

With these simple measures, you can already make a noticeable improvement. Sometimes less effort means more benefit 😉 Good luck!

tutan schrieb:
The good news is that you can do quite a bit without tearing down the entire shelf or installing high-end insulation panels 😉

In addition to tutan’s tips, I would like to take a more technical look at the topic because there are some important details.

The reflections on the inner surfaces of the BILLY shelf result from the combination of the smooth particleboard and an existing back panel, which is usually also hard and thin. This creates standing waves and increases the reverberation time, especially in the mid and high frequency ranges, which actually makes the sound louder and less pleasant.

A proven method is to partially or completely replace the back panel with a sound-absorbing layer. Examples include specialized absorber boards made of melamine foam (e.g., Basotect) or a more affordable option like acoustic foam fixed in place with spray adhesive.

The thickness of the insulation is important: at least 2-3 cm (1-1.2 inches) is advisable, otherwise the effect is minimal. In addition to the back panel, you can also attach thin absorbers to the side panels to further reduce diffusion and reflections.

I also recommend not placing the speakers directly against the back panel. A distance of 10-20 cm (4-8 inches) reduces feedback and improves the sound quality.

One last note: the shelf itself should not be underestimated as a sound reflector. Alternatively, you can slightly decouple the back panel, for example with spacer strips, so it does not rest directly on the shelf and resonate.

Lazaroge, how large are your speakers and at what height are they usually positioned? This information could be useful for more advice.

lorena schrieb:
The reflections on the inner surfaces of the BILLY shelving unit are caused by the combination of the smooth particleboard and an existing back panel, which is usually also hard and thin.

That is correct to some extent, but I would like to critically add here whether insulating the back panel alone is really the best solution.

Depending on the exact position of the shelving unit (e.g., proximity to the wall, room size), other factors such as bass reflections from the floor and ceiling could play a more significant role than the smooth surfaces of the shelving unit itself.

Furthermore, increased insulation can sometimes lead to a “dead” sound character, which not everyone finds pleasant. It is important not to aim for maximum soundproofing in general, but rather to target the problematic frequencies — so rather a combination of absorption and diffusion.

lazaroge schrieb:
I’m thinking of measures like insulating the back panel, avoiding hard surfaces, or adding sound absorbers, but I’m not sure which solutions really work in everyday use and how to implement them best.

From my point of view, it’s worth measuring the dominant frequency of the reverberation time using either measurements or an app before making major changes. This way, you can plan bass traps or absorbers more precisely and avoid unnecessary effort and costs.

I would also suggest experimenting with furniture arrangements. Sometimes, simply slightly repositioning the shelving unit or speakers can positively influence the reflections.

What type of speakers are you using exactly (bookshelf speakers, floor-standing speakers, active speakers)? This also affects how effective the measures will be.