skip to Main Content

Sound Absorption Coefficient Testing

Categories: ,


Sound Absorption Testing

Impedance tube + AFD software + Multi-channel instrument by SINUS Messtechnik GmbH

The impedance tube AFD 1000 – AcoustiTube® measurement system determines the sound absorption and reflection coefficients, as well as the impedance ratio, of material samples in a laboratory based on the DIN EN ISO 10534-2 transfer-factor method.

The measurement results allow direct determination of the rated sound absorption coefficient of a sample according to DIN EN ISO 11654.

AcoustiTube is based on a measurement technique in which a plane sound wave is emitted towards a sound-absorbing material sample in front of a reverberant termination within the impedance tube. The resulting sound pressure is measured by two microphones in front of the sample. The two microphones are connected to a multi-channel instrument, such as the Soundbook, Noise PAD, Expander/Apollo/Apollo Lite Box (plus laptop) by SINUS Messtechnik GmbH. The AFD software is used to communicate with the acquisition device and perform the measurements.

Sample holders

Depending on the application field different sample holders are available.

Sample holder I

Application field: Determination of the sound absorption coefficient in a laboratory according to DIN EN ISO 10534-2.

Samples: Cylindrical samples with a diameter of 15mm, 30mm, 40mm or 100mm.

Application: Mounting and soundproof sealing of prepared cylindrical samples of variable thickness on continuously adjustable and lockable sample holder.

Sample holder II

Application field: In-situ determination of the sound absorption coefficient according to DIN ISO 13472-2 (sound absorption coefficient < 0.15).

For samples of road surfaces and plate-shaped samples with minimum dimensions of 300mm x 300mm

Adapter for soundproof attachment of the impedance tube to a sample surface.

Compression sample holder

The compression sample holder is an extension to the impedance and transmission tubes. It is almost continuously adjustable in length. Furthermore the compression sample holder allows defined compression of cylindrical samples or bulk sample material for determination of the sound absorption coefficient. Finally it facilitates controlled installation of thin materials


AFD 1000.1 Impedance Tube Software

The AFD 1000 software is a comprehensive, high-performance engineering tool for the frequency-dependent determination of material characteristics. AFD 1000 enables the averaging of results from different material samples, to easily manage and compare results using a database and to determine the sound absorption and reflection coefficients as well as the impedance ratio of test objects in the laboratory based on the DIN EN ISO 10534-2 transfer-factor method.

AFD 3001 – Acoustic Design of Multi-Layer Systems (802054.0)

In addition, the AFD 3001 software allows the acoustic design of multilayer systems by means of a graphical user interface.

Input parameters

  • environmental conditions
  • thickness of material setup
  • material parameters, e. g. length-related airflow resistance; tortuosity; structure factor; porosity calculation models / measured data: Air and open porous absorbers. Model according to DELANY-BAZELY; model of homogeneous medium; phenomenological model; complex absorber values measured in the transmission tube (continuous spectrum)

General technical specifications of AcoustiTube

15mm impedance tube

Inner diameter     15mm

Frequency range     150 … 10200Hz

30mm impedance tube

Inner diameter     30mm

Frequency range     150 … 6600Hz

40mm impedance tube

Inner diameter     40mm

Frequency range     100 … 4400Hz

100mm impedance tube

Inner diameter     100mm

Frequency range     50 … 2000Hz

Sample thickness

AFD 1000     260mm

AFD 1200     80mm

Compression sample holder     170mm

Back To Top