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Технически университет - София

Abstract: Impedance tubes are used to measure the acoustic impedance of a sound absorbing material and are essentially one-dimensional wave guides, with a source at one end and the acoustic load – typically the test sample of the absorptive material – placed at the other end. There are two common methods by which the impedance of the material is measured in an impedance tube. The first involves a moveable microphone that traverses the length of the tube. This method is the older and arguably simpler of the two methods but is slow. The second method is known as the “two-microphone” or “transfer function” method and will be the focus of the method employed in this section. In this study will be modeled a 3D impedance tube with a complex termination using finite element method software and the results will be compared with experimental data.

References

1. Pleshkova Sn., 2012, Basics of Video and Audio Teschnologys, Sofia, TU Sofia
2. ISO EN 354:2003.Acoustics: Measurement of sound absorption in a reverberation room
3. [2] ISO EN 10534-1 - 1996. Acoustics: determination of sound absorption coefficient and impedance in impedance tubes. Part 1: Method using standing wave ratio.
4. [3] ISO EN 10534-2 - 1998. Acoustics: determination of sound absorption coefficient and impedance in impedance tubes. Part 2: Transfer function method.
5. [10] ANSYS, Element Reference Manual, ANSYS, SAS IP, 2011

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