Principle of “In situ Absorption”
The basic components of the measuring system are a spherical loudspeaker as well as a PU probe of the company Microflown Technologies that is installed at a defined distance to the loudspeaker. The loudspeaker emits a test signal. The determination of the sound absorption coefficient occurs by simultaneous measurement of the complex quantities sound pressure and particle velocity by means of the PU probe in the direct vicinity of the material to be investigated.
The extraction of specimens is not required. Thus, the evaluation of the acoustic homogeneity of structured and near-net-shape surfaces is possible as well. The separation of incident and reflected sound waves occurs by evaluation of a reference measurement without specimen.
In contrast to the application of the impedance tube AED 1000/1200 – AcoustiTube®, the sound absorption coefficient can be also determined at angles of sound incidence differing from 90° (perpendicular sound incidence).
The measuring system is supported by the analysis software “Impedance“.
- determination of sound absorption coefficient, sound reflection coefficient and acoustic surface impedance depending on frequency
- intuitive graphical user interface
- simple data management and possibility of comparison of results
The optional analysis software “Scan&Paint” enables the visualization of the sound absorption coefficient as colored, two-dimensional distribution in connection with a photograph of the test object. Thus, measurements regarding the homogeneity of acoustic properties of open-porous materials and structured surfaces can be efficiently and easily carried out and documented.
This represents a big advantage, especially with respect to quality control of sound absorbing materials during the manufacturing process as well as end of line control at assembled substances (e. g. sound absorbing components of vehicle interiors).
Besides the sound absorption coefficient, the acoustic quantities measured by the PU probe, like sound pressure level and particle velocity level, can be mapped as colored distribution as well.
Design, consultancy and seminars
From the development, over the evaluation, up to the optimization of sound absorbers, we like to provide our specific technical knowledge. For that purpose, besides a training of your staff members regarding the handling of the measuring system “In situ Absorption”, we offer you various seminars and trainings courses in the field of technical acoustics.
Furthermore, on request, we support you with the acoustic design and the evaluation of sound absorbers with respect to various applications. This includes especially the utilization in the area of building and room acoustics as well as noise reduction in terms of mufflers and silencers, noise screens and enclosures.
Impedance measuring system
- typical frequency range: 300 Hz – 10.000 Hz
- recommended dimensions of specimen with respect to material characterization (length x width): 30 cm x 30 cm
- distance between loudspeaker and PU probe: 25 cm
- maximum sound pressure level of loudspeaker at PU probe: 111 dB
- required minimum signal-to-noise ratio: 10 dB
- weight: 1,04 kg
- Personal computer: Windows 2000 / XP / Vista / 7 / 8,
* “In situ Absorption” is a trademark of the company Microflown Technologies