Abstract

The present thesis deals with the development of an impedance pipe measurement system for determining acoustic material parameters (reflection coefficient, absorption factor, acoustic impedance, acoustic admittance) of acoustic absorbers on the basis of the transfer-function method.

The description of the theoretic approaches according to ISO 10534-1 and ISO 10534-2 is followed by a discussion of both measurement systems and a comparison of the standing wave ratio measurement method with the transfer-function method (2p method). The advantages of the transfer-function method are explained in detail. The third chapter focuses on the adaptations required to account for the theoretic approaches to the measurement system. After that two impedance pipes, with round and square cross-sections (with a diameter of 10 cm resp. cross-section side length), are developed, which can be used with the studio microphones B&K 4006 and AKG 480. Subsequently, the code controlling the measurements in MATLAB 5.3 on the Windows 98 platform is described.

The last section contains comparison measurements conducted with a commercial impedance pipe measurement system by Brüel & Kjaer. The efficiency of the developed measurement device is verified on the basis of the measurement results. This is followed by a comparison of both pipe cross-sections and microphone types, and the documentation of the obtained results.
Finally, an outlook on possibilities of extending the measurement system is presented.

Full Text and additional Material

You can download the full version of the diploma thesis here.

Notice

As the Acoustics and Audio Group moved in 2002 from the Institute of Communications and Wave Probagation (INW) to the Institute of Broadband Communications (IBK) and in 2011 to the Signal Processing and Speech Communications Laboratory (SPSC), the puplishing location of this thesis also was transfered from the INW to the SPSC-website.