Noise regulation

Sound insulation is about dampening the direct noise, e.g. through a wall.

When you have to describe how good a wall (or something else) is at reducing direct noise, you use the reduction number R, which is measured in dB.

A high number means that the sound is strongly attenuated when it passes through the wall (or something else)

The reduction figure usually varies greatly with frequency.

When assessing soundproofing properties, it is therefore necessary to know how the frequency content is in the sound that needs to be dampened.

The reduction numbers in the different frequency bands can be added up to a single number, the weighted reduction number, which is called RW and is suitable for speech and noise, which generally have a wide frequency spectrum.

More narrow-band noise should be evaluated based on R in the respective frequency band.

When you evaluate stated R and RW, you must note that they are measured under laboratory conditions.

It is therefore our rule of thumb that the real reductions are a few dB lower:

• For R above 60 dB, 6 dB should be deducted
• At R between 50-59 dB, 5 dB should be subtracted
• At R between 40-49 dB, 4 dB should be subtracted
• Etc

Noise can be transmitted in many ways, in addition to through walls, e.g. through doors, windows, leaks, installations, etc.

Sound through walls

For the simple wall consisting of solid board, the insulation is determined that the weight of the board per flat and of the frequency. Theoretically, R increases by 6 dB every time the frequency is doubled or every time the plate weight is doubled.

R improves significantly if a double plate wall is used and even more so with absorbent between the plates.

Our MATADOR walls are optimal for soundproofing as:

• Is a double plate steel wall
• Is made of steel, thus heavy
• Has heavy absorbent between the sheets
• Standard takes up only 60 mm
• Standard has RW 44 dB
• Can be adapted to any desired RW

Sound through doors and windows

Sound-insulating doors and windows are available in 6 categories 25, 30, 35, 40, 45 and 50 dB. They can be expected to have a RW of at least the labeling value minus 3 dB when installed according to the manufacturer’s instructions. It is important that the seals between the wall and the frame are made carefully.

A great sound insulation of windows can be achieved via so-called sound windows, which are double-layered glass, where the 2 glasses have different thicknesses.

Our MATATOR windows and windows in doors are characterized by the fact that they can be adapted to all of the above 6 categories.

Openings

Openings, e.g. holes and gaps, can significantly reduce sound insulation.

It may be necessary to have holes in the wall for transport systems, ventilation, pipe passages and the like. The holes should therefore be fitted with sound barriers or otherwise sealed.

At Skov Industri, we have 35 years of experience in carrying out these seals and sound barriers.

The reduction number for a composite surface

A wall, e.g. in a machine enclosure, must normally be provided with windows and doors, ventilation and much more. This will usually result in a lower noise isolation than the wall itself.

If you know the area conditions and the RW of the individual elements, it is possible to calculate the total RW for a composite cabin, and we naturally take that into account.

Requirements for airborne sound insulation

The requirement for airborne sound isolation of a separation between a noisy and non-noisy area should at least ensure that the company’s current noise level can be met.

If you have any questions about sound insulation, please feel free to contact us, it is non-binding.

Sound screens are a common term for fixed or mobile screens between noisy and quiet activities, often called screen walls, as they can screen for things other than noise.

Especially if the sound is high-frequency, and you can place the screen wall close to the noise source, you can often dampen the noise simply by using a screen wall.

Requirements for a free-standing screen

In order to achieve maximum utilization of the screen, one must avoid that the sound is reflected from the limiting surfaces of the room.

• The most important thing is that the ceiling is sound absorbent, at least in an area above the screen
• Place the screen as close to the noise source as possible, alternatively as close to the receiver as possible
• The side of the screen facing the noise source should be absorbent
• The screen must be at least so high that the line of sight between noise source and receiver is broken, and the higher the screen wall, the greater attenuation is achieved
• The screen should be able to withstand the chemicals and cleaning agents used
• In practice, it is our experience that a screen’s attenuation rarely exceeds 15 dB. We can pre-calculate how much attenuation our screen walls will provide

See more about our screen walls here

You are also welcome to contact us if you want to know more about screen walls