LABORATORY

A good airbone sound and impact sound insulation is essential so that several people can live and work in a building without any problems.

In the acoustic laboratory we have the facilities to test the acoustic characteristics of building products.

Following standard test stands are available: 

• Impact sound test stand
• Window test stand
• Door test stand
• Wall test stand
• Echo chamber
• Impedance pipe ((Kundt'sches pipe)

The measurement of the improvement extent of impact sound insulation takes place in a test stand made up of two rooms put on top of each other. These are separated by a 14 cm thick armoured concrete ceiling.

The sound stimulation is done with a standard hammer mill. This consists of five hammers of 500 g each which pitch from a height of 4 cm and with a stroke frequency of 10 impulses per minute on the ceiling or a floor cover. Of the differences between the airbone sound levels under the stimulated room ceiling – with and without floor cover - result the “impact sound level reductions”.

Typical floor covers:

• Carpet
• PVC flooring
• Floor screed construction
• Prefinished hardwood floor or laminate on impact sound insulation underlayer
• etc.

Sound insulation measurements are normally done in an echo chamber. This echo chamber has a volume of 200 m³ and shows in case of sound stimulation an diffuse sound field which occurs due to the bevelled limited components and suspended (thin) plates (made up of plywood, aluminium etc.).

The reverberation times (the dying out after a sound stimulation) are quite long. Depending on the frequency and devoid of built-in testing objects  in the deep frequency areas (below 200 Hz) reverberation times of 6 seconds are common, at frequencies of 1.000 Hz times of 3 seconds and at frequencies of 4.000 Hz of 2 seconds. 

Using built-in testing objects (carpets, suspended ceiling, etc.), which are in general displayed on the echo chamber floor with a typical size of 3 m x 4 m (in normal case 10…12 m²), results in appropriate shorter reverberation times. 

The sound absorptions rate can be defined on basis of the reverberation times with and without the testing object (carpets, suspended ceiling etc.). 

Typical sound absorber

• Carpet 
• Suspended ceiling
• Partition walls
• Curtainings
• etc.