PLACID Instruments Impedance Tube sound absorption and transmission loss

PLACID Instruments impedance tube (designed and tested in the Netherlands) is used to accurately testing sound absorption and transmission loss without the need of reverberation or anechoic room.

The PLACID PI series Impedance Tubes can accurately measure sound absorption coefficients as well as transmission loss
according to both ISO and ASTM standards. 

Easy to use software, highly accurate and high-quality DAQ, 1/4″ microphones and stable software.

3 sizes of impedance tubes (16, 30 and 100 mm) to cover the  frequency range of 50 Hz up to 10 kHz.

Download the datasheet.

The results can be used to compare the basic absorption performance of the material and for acoustics simulations.

In practice, the absorbers can be quite large, and their structure and configuration may be complex and part of acoustic designs. Furthermore, they will be exposed to real sound fields where the incident sound may come from many directions.

The PLACID impedance tube kit consists of 2 or 3 tubes with a diameter of 16, 30, and 100 mm to cover the whole frequency range. At the end of the tube, a loudspeaker is mounted and will emit a precisely quantified sound generated by the signal generator and amplified by the amplifier. The 4 channel Data Acquisition System (DAQ) will gather and record all measurement data and relay it to the software.

The microphones will measure the sound level at each given position. The software will then calculate the normal incident acoustic properties of the material based on the frequency response functions measured between the various measurement locations.

The Impedance tube kit can determine the sound absorption coefficient as well as the transmission loss.

PI8810, 100 mm impedance tube, frequency range 50 Hz – 1600 Hz

PI8803, 30 mm impedance tube, frequency range 800 – 6300 Hz

PI88016, 16mm impedance tube, frequency range 2500 – 10000 Hz

Impedance tube can measure sound absorption coefficient as well as transmission loss, ISO10543-2, ASTM E1050-08.

Microphones used: 1/4″ Class I or class II , 20 Hz to 20 kHz (BNC to SMB connector).

Applications for Impedance Tube

  • testing of material characteristics and verifying material compliance before implementing the materials in the assemblies
  • design of acoustic comfort in aircraft, helicopters, ships, yachts, and vehicle interiors by selecting the optimal acoustic treatments and noise barriers
  • research and development of noise control products by benchmarking competitive products
  • research jobs for students and universities
  • validating and calibrating theoretical computational methods such as acoustic modeling

Define material Characteristics

Materials in an acoustic application typically either are used for sound absorption or for noise transmission loss. Acoustic designers need to know the exact noise characteristics of a material to be able to make predictions. Testing a material in the Impedance Tube is quick and precise.

BSWA Impedance Tube sound absorption and transmission loss

The Kundt tube, also known as Impedance tube is an instrument that is used to easily testing sound absorption and transmission loss without having to go to a huge anechoic room.

The SW series Impedance Tubes can accurately measure sound absorption coefficients and impedance according to both ISO and ASTM standards. They also support the sound transmission loss measurements based on the Transfer Function Method. The Transfer Function Method separates the incident and reflected energy from the measured transfer function, and then estimates the acoustic properties of the tested sample installed in the tube. 


Overview of Impedance tube system for pavements absorption test SW420R

ISO 13472-2: 2010 specifies a test method for measuring in situ the sound absorption coefficient of road surfaces with impedance tube. This method enables evaluation of such characteristics without damaging the surface. SW420R is designed according to ISO 134722, and the performance satisfies the requirement of ISO 13472. The test results can the absorption characteristics of road surface for vehicle, tyre testing and other traffic noise studies. However, the field of application is limited to low absorption surfaces, such accordance with ISO 18044. The method is not reliable if the measured sound absorption coefficient exceeds 0.15. The use of SW420R is the same as description in ISO 10534, VA-Lab IMP module can be used with SW420R.

• Specially designed for measurement of sound absorption
• Properties of road surfaces.
• Integrated design, portable and stable.
• Selected sealing material, reducing the leak of sound signal.

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