Acoustic panels, foams, soundproofing mats, and insulation systems are often presented as similar products. In reality, they serve entirely different functions.

Sound-absorbing materials limit sound reflections within a room. On the other hand, soundproofing solutions reduce the amount of sound transmitting through walls, ceilings, doors, and other partitions.

Confusing these two properties is one of the most common causes of ineffective "soundproofing."

An acoustic panel on the wall, yet the neighbor is still heard

Let us imagine a typical scenario. Conversations, music, or television sound drift in from the neighboring apartment. Seeking a solution, we come across acoustic panels. We glue them to the wall and notice a change. The room sounds less hollow, the voice does not reflect as strongly, and the interior seems calmer.

However, when the neighbor turns the music on again, it turns out that it is still audible in almost the same way. Does the solution not work? It does work, but for a different issue. It has limited sound reflections in the room, but it has not significantly increased the acoustic insulation of the wall.

How do acoustic panels work?

The term "acoustic panel" is most commonly understood to mean a sound-absorbing panel. This can lead to the misconception that absorption means the complete elimination of acoustic energy. Unfortunately, this is not the case.

A sound wave, when hitting an obstacle—for example, a sound-absorbing panel—undergoes (in simplified terms) the following phenomena: reflection, absorption, diffraction, and transmission. If we consider residential conditions, the diffraction of a sound wave on a partition should not concern us, as this rather relates to environmental and industrial acoustics. Let us focus on reflection, absorption,
and transmission.

Sound absorption is therefore related to the coefficient of acoustic energy absorption. It corresponds to the percentage of acoustic energy that returns to us after being reflected. Thus, the higher the absorption, the less energy returns to us.

Sound transmission through a partition

This is linked, among other things, to the partition being set into vibration by the incident acoustic wave. For example, a sound wave reaching a wall causes it to vibrate, and part of the energy is subsequently radiated on the other side of the partition. The more susceptible a wall is to vibration, the greater the sound transmission can be.

Similarly, any lack of airtightness opens the way to additional, unwanted sound transmission. Therefore, if we are talking about sound transmission through a wall, it is important for the wall to be heavy or structurally decoupled, for example, with a layer of rubber that acts as a vibration dampener.

The best approach is to use a multi-layered system consisting of
acoustic plasterboards (increased mass) and a layer of rubber between them (vibration damping). It is important to remember that this will not reduce reflections in the room, as hard and smooth surfaces, even if they effectively limit noise transmission to neighboring interiors, can still strongly reflect sound and contribute to excessive reverberation.

One should not assume that…

…any "acoustic panel" will solve any noise problem. Properly selected panels can indeed improve acoustics; however, if used contrary to their intended purpose, they will operate in a different area than the user expects.