The term soundproofing

defines the method of separating rooms acoustically

In order to make optimum usage of the rooms, a good sound insulation is required by the user.
Here, an important factor is the sound reduction index Rw,P, which is tested in the laboratory.

In this respect, BLS offers a selection of eight different sound insulation values:
Rw,P 44 dB, Rw,P 48 dB, Rw,P 51 dB, Rw,P 52 dB, Rw,P 54 dB, Rw,P 55 dB, Rw,P 57 dB and Rw,P 59 dB.

 

Wall thickness / element thickness
With a sound insulation of Rw,P 44 dB to Rw,P 55 dB, in combination with a standard plastic surface, the wall thickness is 100 mm. Due to more sound insulation material used for a sound insulation of Rw,P 57 dB to Rw,P 59 dB, in combination with a standard plastic surface, the wall thickness is 120 mm.
Through the use of other surfaces such as acoustic panels, the wall thickness is increased to about 130 - 160 mm.

General information on the sound insulation of movable walls

The sound insulation of movable partition walls is measured on the acoustic test stand in the laboratory under conditions without any­ secondary sound channels.
The sound reduction index is specified as Rw or as Rw,P.

Because of existing­ secondary sound channels via flanking structural parts, this sound insulation cannot be reached by the partition wall on site. Therefore, the flanking structural parts­ must also meet demands concerning their acoustic performance. Depending on the level of sound insulation to be achieved, these demands are designed differently. This may reach a point where additional noise control measures will be necessary as determined by an acoustician.

The sound insulation of the flanking structural parts should be approx. 10 dB above the sound insulation of the movable wall system. Nevertheless, there is a reduction of the sound insulation as a result of secondary sound channels, which are deducted with a set value of up to Vm  10 dB.

 

The illustration shows how the sound insulation of the individual components is composed.

Example calculation:

The movable wall system used was measured in the laboratory with Rw,P 51 dB.
Taking into account the set value of Vm 10 dB, the expected value of the installed item is Rw,R 41 dB.

The flanking structural parts such as walls, windows, doors, floors and ceilings are not considered in this example;
however, they have a huge impact on the actual sound insulation. For example, ventilation ducts and cable bridges in the suspended ceiling and in the partitioning may reduce the specified sound insulation value.
A standard value for built-in doors and windows is in the range of Rw,P 32 – 39 dB, which also affects the total sound insulation value.

 

The calculation of the resulting sound reduction index Rw,res is done according to the following equation:

What is the achievable sound insulation with a partition wall with a surface of ​​Smovable wall 12.6 m², a glass brace of Sfacade brace 2.2 m², a concrete column with a surface of ​​Ssolid component 1.2 m² and a total surface of Str 16 m²?

Calculated value of the sound reduction index of the individual components in dB

Rw,R,movable wall

Rw,R 41 dB

Rw,P 51 dB - Vm 10 dB

Rw,R, solid component

R'w,R 52 dB

 

Rw,R,facade brace

Rw,R 32 dB

Rw,P 37 dB - Vm 5 dB

In our example, the result of the sound reduction index is Rw,res 38.2 dB.

For common office work, the VDI directive recommends a sound insulation value of R'w 37 dB between rooms.
In order to achieve this sound insulation, based on the previous example a movable partition wall with Rw,P 51 dB is required.

Increasing the sound insulation by Rw,P 6 dB to Rw,P 57 dB, the resulting sound insulation value is increased by only 1.7 dB to Rw,res 39.9 dB.

 

Example:
In the next room, a loud conversation with a noise level of 70 dB (A) is insulated by a wall with a calculated sound insulation of Rw,res 38 dB. The conversation can still be heard with a residual noise level of about 32 dB (A) – understanding and tracking the conversation is no longer possible, though.

Perception and sound insulation

Sound insulation (total)

Perception by user

30 dB

A conversation in the next room can clearly be heard and understood.

35 dB

A conversation in the next room can be heard but not understood.

40 dB

A conversation in the next room is perceived vaguely.

50 dB

A conversation in the next room cannot be heard.

The sound level

0 dB (A)is the hearing threshold of people with normal hearing.

0 to 20 dB(A)

Hardly to be heard – such as forest noise or whispers.

20 to 40 dB(A)

Already good to hear – such as fans and general background noise.

40 to 60 dB(A)

A normal conversation sound level or a soft radio.

60 to 80 dB(A)

Achieved by a loud conversation, a passing car or a vacuum cleaner.

80 to 100 dB(A)

The range of a passing truck, a chain saw or a disc grinder.