System for determination of materials impedance in impedance tubes

System for determination of materials impedance in impedance tubes is used for evaluation of material’s acoustic properties.

The system meets the requirements of applicable standard ISO 10534-2:1998 «Acoustics – Determination of sound absorption coefficient and impedance in impedance tubes – Part 2: Transfer-function method».

Measured parameters

Sound absorption coefficient
Reflection coefficient
Acoustic impedance

Operating principles

The specimen is placed inside of a solid, leak-proof, smooth impedance tube. The noise source generates broadband noise, then the sound pressure is measured at two points near the tested specimen. The transfer function calculated based on data from the two microphones is used for calculation of the required values.

FFT spectrum analyzer ZET 017-U4 is used for generation of the broadband noise and processing of signals received from the microphones. The noise generated by FFT spectrum analyzer is produced by the dynamic placed inside of the impedance tube. Two microphones inside of the impedance tube are used for acoustic pressure measurements.

Scheme of the stand for measuring the strength of materials

Frequency range depends on tube diameter and the distance between the microphones. It is also possible to achieve an extended frequency range by performing a number of tests with various diameters and distances.

Prior to measurements performance, it is necessary to calibrate the system so that to reduce the difference between characteristics of the microphones (i.e., amplitude, phase).

Advantages of the system

Compact dimensions

minimum space required


minimum interference impact on measurements results


software enables automated parameters calculation


certified instruments used within the scope of the system

System components

Basic configuration
Item Function Amount Price USD
FFT spectrum analyzer ZET 017-U4 controller for processing of the signals received from primary transducers 1 pc 7896
SW422+SW477 accurate measurement of sound absorption corfficient 1 pc from 16584
Amplifier PA50 control of the sound pressure produced 1 pc from 1129
Microphones MPA 416 sound pressure measurement 2 pcs from 625
Calibrator CA115 microphones calibration 1 pc from 507
Software “Impedance measurement system” SCADA-project for material’s acoustic properties evaluation in automated mode 1 pc 2889
SCADA system ZETVIEW necessary option for operation of SCADA-project 1 pc 349
Cable CBB005
Cable CBS055
Cable CAA002
for connection of PA50 to ZET 017
for connection of MPA416 to ZET 017
for connection of PA50 to the speaker
1 pc
2 pcs
1 pc

POR (price on request)

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