Sound absorbers for home and office

In many rooms there are problems with reverberation: one can tend to hear one’s own voice bouncing right back at them. Sound absorbers can provide a solution to this issue. To avoid your home or office looking like a recording studio, it's a good idea to use sheep's wool felt.

Here we’ll demonstrate how you, as a carpenter or interior decorator, can use natural wool felt to produce effective and visually appealing acoustic panels.

Properly processed sheep's wool has extremely good properties in the acoustic room optimization. Silentum sheep's wool felt has a high density and is nevertheless open-pored and flexible. From an acoustic point of view this means:

• Sound waves of different frequencies are refracted in the felt layers and thus not reflected into the room, but absorbed by the felt.
• Sheep's wool felt dampens especially low or particularly high tones very effectively.

In addition to its acoustic properties, sheep's wool has other characteristics that no other acoustic product can match:

• Room air improver: Sheep's wool improves the room air because it filters pollutants sustainably. Such as the formaldehyde found in MDF boards.
• Climate regulator: Sheep's wool regulates the room climate: the new wool absorbs excess moisture in the room air and releases it again when the air is dry.
• Fire protection helper: Sheep's wool has a very high flash point. The acoustic felts are therefore flame retardant and in case of fire there is hardly any smoke formation.
• Dirt repellent: Sheep's wool is naturally dirt repellent and therefore a very handy product in daily life.

After the felt is wallpapered onto wooden boards for the construction of the acoustic absorbers, we advise hiring a professional with the necessary know-how and tools to produce the absorbers.

Alternatively, any motivated and well-equipped “do-it-yourself” homeowner can of course build their own acoustic panels with a few adjustments to the workflow.

Our final result is acoustic panels with a sound absorption coefficient of αw=0.85 (H).

Tools needed

• Circular saw or boards cut to size from the hardware store or from the carpenter
• Cutter knife and cutting bar (for precise felt cutting)
• Glue roller or large brush (for applying the glue)
• Tacker (at best compressed air or electric tacker)
• Scissors
• For the professional: veneer press

Materials Needed

• Blockboard / Three-layer board 18mm
• Soft fibre board 15mm
• White glue (PVAc glue)

The quantity and the dimensions depend on how many absorber panels in which size you want to manufacture.

Note: when making larger acoustic panels, at least one other person should assist you in placing the acoustic felt (step 4) and in lifting and turning the panels.

1. Step: Prepare the wooden boards
   
   We recommend a blockboard or three-layer board with a thickness of 18mm as the basis for a stable construction. For the upper layer you use a soft fibre board with a thickness of 15mm. This board, together with the sheep's wool felt, ensures that your final product achieves a sound absorption coefficient of αw=0.85 (H).

   You join the two boards by applying low-formaldehyde white glue (PVAc glue) to the wooden board with a glue roller or brush and then placing the soft fibre board on top, pressing both boards together.

   Without the press, you should wait about an hour with the further processing, so that the glue dries, works and the two plates are thus well connected.

   Caution: when working with wood, make sure that no shavings get onto the felt surface, as these can adhere very stubbornly to the wool.

    

2. Step: Cut the felt to size
   
   

   
   
   The delivered felt rolls are 1-10 meters long, depending on the order. Before further processing, cut the acoustic felt to your desired size. Make sure that you fold the felt over once on the back of the panel for fastening (step 6).

   In our example, we use 33mm for the panel thickness and another 7-10mm to fix the felt on the back with the stapler. In total, this is a surcharge of 40-45mm on the target dimension.

   With a good cutter with a sharp, sturdy blade and a cutting bar, you can easily cut the felt.
   
   

3. Step: Apply glue
   
   

   
   
   Now prepare the surface with glue: to do this, apply white glue to the softwood panel again using a glue roller.
   
   Make sure to spread the glue evenly so that the entire surface is covered with glue up to the edges.
   
   
   

4. Step: Laying the acoustic felt
   
   
   
   

   Carefully place the acoustic felt on the glue-treated side of the wooden panel. Smooth out the felt by hand and make sure that there is no unevenness.

   White glue normally allows small corrections. You can therefore still get rid of any unsightly wrinkles or waves. It is best to pay attention to the open time indicated on the glue. This way you know exactly how much time you have until the glue becomes active.

   
   
   
5. Step: Pressing felt and plates
   
   

   
   
   For professionals: In order to achieve an optimal connection and to be able to continue working quickly, you must now place the panels with the felt in the press for approx. 5 minutes and press at 80 bars with approx. 62-70°.

   For the do-it-yourself enthusiast who does not have a professional press at hand, a little waiting time is called for. Give the glue about an hour to work optimally.
   
   

6. Step: Staple the acoustic felt
   
   

   
   
   Carefully turn the board over and fold down the overhanging acoustic felt. Fix the felt with the stapler and place the staples close together.

   It's easier with a compressed air or electric stapler. This saves both time and energy. If you are not afraid of using more muscle, you can also use a hand tacker.

   Make sure that the staples are high enough to penetrate the 9mm felt and sit firmly in the plate. Narrow back staples or fine wire staples with a depth of 6-10 mm are best.
   
   

7. Step: Cut off overhangs
   
   
   
   Finally, cut off the double-layered, protruding felt at the corners with scissors. This prevents unevenness and makes assembly easier.
   
   

Depending on where you want to mount your acoustic panels, you can choose from a variety of mounting options. Make sure to always consider the weight of the panels when choosing the mounting method.

Mounting on feet: If you want to use your sound absorbers freestanding, we recommend feet. This way you can also use the modules as room dividers and remain flexible in the placement.

Ceiling mounting with wire suspension: Using it as a ceiling canopy with wire suspension allows for an airy design and also allows you to regulate the height of the room. In addition, you can also plan ceiling lights well.

Mounting with wall or ceiling strips: With our prefabricated Silentum acoustic panels, we work with wooden mounting strips. This allows a rather flexible placement of the different modules. You can find more information about mounting with wall and ceiling strips here.

Mounting directly on the wall: For this purpose, recesses are milled into the back of the modules with normal dowels and screws, you can now hang your modules directly on the wall without the distance of the mounting strips.

A wall suspension with wire, as known from pictures is not ideal. The weight of the panels is a major reason for this. Also, if you want to combine several modules into an acoustic wall, the alignment with a wire suspension becomes difficult.

Acoustic absorbers made of sheep's wool felt are stylish elements in acoustic room design. They serve as sound insulation and provide living space design at the same time. Moreover, virgin sheep's wool is a sustainable, high-quality natural product with many positive properties.

Sheep wool felt is easy to work with and the acoustic panels are simple to install.

It is not for nothing that acoustic felts and sound absorbers made of wool felt are often used in offices, health care facilities or public buildings such as kindergartens and schools.

Mit den Silentum Schafwollprodukten bieten wir ein breites Spektrum an akustischen Produkten an. Nicht nur der Schallabsorbtionsgrad überzeugt: Ein extra Plus sind die gesunden Eigenschaften der Schafwolle, die dein Raumklima verbessern. Ob Lamellen- oder Akustikfilz als Meterware oder bereits rundum fertige Absorber-Module, du hast die Wahl - sieh dich in unserem Shop um.