Bass resistant lightweight partition wall

By means of some additional wooden slats a lightweight construction partition wall
gets a good acoustic damping

Our living room had an open connection to the corridor, which acted like a bass reflex port directing and amplifying the lower notes into other rooms.
When we expanded our sound system to 5.1 sound including a subwoofer, a partition wall had to be constructed that shields bass from the other rooms. The solution should be lightweight and produce low costs.

Construction of the bass dampening lightweight partition wall

 

Photo 1: Framework of the partition as usual

Photo 2: These wooden boards enormously improve attenuation

First bolt U-rails to the floor and ceiling as usual, then fix the vertical profiles (photo 1).

The next step is to establish one complete side of the partition wall.

Now the crucial step comes: You have to stiffen all joints between the boards with thick wooden planks from the back. These boards should extend across the whole length of the joints photo 2).

Installation is simple. You need a helper, who is holding the wooden slats from the back side. They are screwed from room side with the same self cutting screws also used to screw the boards to the frames. Tighten these screws so that the heads get into in the gypsum boards. (Later, all joints and screw are filled.)

The assembly of the second wall, is shown in the following illustration:

mounting the bass resistand wall

Mounting of the bass resistant wall in three steps.

Fig. 1 shows the assembly of the first wall as described.

Fig. 2 here you can see how the first wooden slat is screwed from the outside after the plasterboard is fixed.

Fig. 3 in the next step, the next plasterboard is screwed to the already fixed wooden slat.
Then the next plasterboard is mounted above as shown in fig. 2. You work in this way from the bottom up.

Results

Before installing the barrier wall the long corridor behind the room acted as a bass channel. In the other rooms we had the feeling that the bass has been ampflified, being heard louder than in the living room.
After installing the wall, we got the following results. The test signal was pink noise, measured both before and behind the closed door:

Frequency response before (green) and behind the door (brown)

Test signal amplitude before and behind the wall

You can listen to the result with this small wave file (160 kB).

Extreme Modding

Best acoustic damping is achieved with mass and a material, that converts the sound waves with its internal friction into heat. In short, with sand.

Therefore one might suggest filling the inner volume between the two plaster walls with inorganic, water-free sand (quartz sand). But this will affect stability of the wall. In principle, also bags filled with sand could be inserted.
(Note: You must not use any sand with organic additives or use wet sand! In both cases, this can start going mouldy, which is very risky for health.)

However, for us, the solution described above, perfectly worked.

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