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In-situ Absorption

In-situ Absorption

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We can offer a complete solution to measure the acoustic properties of materials with the in-situ absorption setup from Microflown Technologies.

There are many unwanted noise sources in our industrialised society but acoustic noise pollution can be reduced by absorbing sound energy. Absorbing material packages are used in many applications to attenuate sound and knowing the exact acoustic properties of your materials and the effectiveness of the applied material packages is a requirement to successfully reducing noise levels. The In-situ absorption setup is a solution to achieve just that.

Destructively taking samples is no longer required and the absorption of sound waves under oblique angles of incidence as they occur in practice can now be tested. The system can even measure complete assembled parts next to material samples. Its extremely high spatial resolution allows the analysis of non-homogeneous (e.g. perforated) materials. The in-situ method also works with a relative movement between a sample and probe which means that end of line control of materials is possible. Curved materials can also be measured so the acoustic package quality in final assembly lines can be tested.

The Impedance gun

With a small, handheld impedance gun, the acoustic absorption, reflection, or impedance can be measured in just a few minutes. All this within a broad frequency range (300 Hz – 10 kHz) and under normal and oblique angles. From a sound source, positioned 23cm away from a PU probe, white noise is generated towards the measured sample. The impedance gun is equipped with a system to decouple the sensors from structure born vibration generated by the spherical loudspeaker. The sound pressure and acoustic particle velocity are measured right on the surface of the material. The absorption and reflection coefficient can be obtained directly from the measured impedance, which is the complex ratio of sound pressure and particle velocity.

Measurement results from the impedance gun are processed through a dedicated software application, which provides a user friendly interface to govern all your measurements regardless of whether they are related to different material samples, or different points within just one sample.

The Kundt’s tube

The PU probe, part of the in-situ absorption system, can also be used for measurements in a Kundt’s tube (standing wave tube). The in-situ absorption software comes with the tools necessary to calculate the absorption and reflection coefficients from a measurement in a Standing wave tube taken with a PU probe (the tube itself is not part of the system). Thanks to this function, you’ll be able to take full advantage of the capabilities of your PU probe and benefit from better estimation of the absorption and reflection coefficients as compared to the two microphone measurement taken in a standing wave tube.


  • Frequency range 300Hz – 10kHz
  • In-situ method
  • Normal & oblique angles of incidence
  • Flat & curved surfaces
  • Homogeneous & inhomogeneous materials
  • Fixed and moving surfaces
  • Can be used for:
    • Product development
    • End of line control before and after assembly

To download the datasheet click here

To download the manual click here