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# Laboratory

As a producer of innovative new products, it is crucial to exactly know the acoustic specifications. One can think of the resistance of acoustic meshes, where an important trade-off has to be made between resistance to unwanted dirt, or water entrance and the acoustic transparency. For building acoustics, an important quantity is the sound absorption coefficient of a material. The experimental determination of acoustic material properties requires a proper understanding of physical acoustics, equipment such as an impedance tube and proper mathematical analysis software. ASCEE's acoustic laboratory contains the right tools to effectively characterize acoustic materials.

## Impedance tube

Our in-house impedance tube is able to characterize acoustic materials, such as porous absorbers and perforated sheets, in a wide frequency range from 40 Hz to 4 kHz. Using our setup and software, we are for example able to determine the following acoustic material parameters:

• Normal incidence sound absorption coefficient ($$\alpha$$)
• Reflection coefficient ($$R$$)
• Normalized impedance ($$\zeta_n$$)
• Acoustic scattering parameters ($$\mathbf{T}$$)
• Delaney-Bazley-Miki (DBM) material parameters
• Johnson-Champoux-Allard (JCA) material parameters

Using these parameters, a simulation model can be created to determine the effect of a sound insulation solution.

## Material database

ASCEE has established a database of material properties of common absorptive acoustic materials, such as foams and fibre wools, which can be used to simulate the noise reduction in a system or room.

## Silencer transmission loss

ASCEE is experienced and able to test custom silencer transmission loss, including flow, for ventilation systems according to the ISO 11 820 (1996).

## Anechoic room

As the word implies, an anechoic room is a room without any echoes. This means that all sound is absorbed by the walls of such a room. Anechoic rooms are typically used to create 'ideal' acoustic situations, i.e. a perfect free field for acoustic radiation.