For characterization of acoustic material properties, such as the sound absorption coefficient, the reflection coefficient, the acoustic impedance and the transmission loss coefficient, it is possible to use the different range of impedance tubes in the laboratory of the SD&A group.
The measurements are based on the two-or four- microphone transfer function method and the data results can be applied for acoustical modelling and to find specified material characteristics.


Impedance tube, Impedantiebuis

Measurements/ Setups:


Tubes with a diameter of 0.05/0.06 and 0.20m

Frequencies from 50Hz until 5kHz


-SigLab 4 channel DSP signal analyzer type 20-42 for measuring the data

-Option: NI 8 channel PXI-4472-8 analyzer (Input 24bit resolution, 102.4 kS/s sample rate) with LabVIEW software.

-Different microphones to measure the complex transfer functions:

----1/4 inch Kulite pressure transducers CXS190m (0.14bar) + conditioning

----B&K 4192- ½ inch microphone + conditioning

-Different Impedance tubes with sample holder

-Speaker with amplifier, which generate a broadband stationary random sound wave. This propagates as plane waves in the tube, hit the sample and reflect.

Detailed overview


Several Master Thesis and publications in the SD&A group



Research group:

Structural Dynamics & Acoustics (part of Applied Mechanics)


B. Wolbert

Application for big samples used to measure the transmission loss coefficient (4p method)