PROGRAMM - DAGA 2012

Programm DAGA 2012 221to combine subjective and objective quality assessment of loudspeakersystems.Mittwoch (ab 13:30, bis Do.)Akustische Messtechnik (Poster)Uncertainty Factors in the Determination of Acoustic ReflectionFactors with pu-ProbesP. Dietrich, M. Aretz, M. Müller-Trapet, J. van Gemmeren und M. VorländerInstitut für Technische Akustik, RWTH AachenHigh-quality numerical simulations in room acoustics require a detailedknowledge of the acoustic reflection characteristics of the materials inthe room, in order to realistically model the interferences between multiplesound reflections at the room boundaries. While different standardizedmeasurement methods exist for the determination of the absorptioncoefficient and reflection factor these methods can generally not beapplied in-situ. Thus time-consuming laboratory measurements and thesupply of material samples are required.Driven by the obvious demand for a reliable in-situ measurement technique,a new pu-probe based method has emerged during the last years,which derives the reflection factor based on the simultaneous measurementof sound pressure and velocity. However, previous investigationsof the setup and publications by other authors have shown that the measurementresults are affected by various uncertainty factors.The present study aims at the identification, separation and quantitativeassessment of the uncertainty factors related to diffraction effects at thesource and sensor, as well as to calibration issues. We therefore conductimpedance measurements in a well-controlled environment and comparethese to results of BEM simulations, where we gradually increasedthe amount of geometric detail of source and sensor to investigate theirinfluence on the measurement result.Mittwoch (ab 13:30, bis Do.)Akustische Messtechnik (Poster)Automatic Classification of Loudspeaker DefectsT. Burstika a , W. Klippel a,b und S. Wiegand aa Klippel GmbH; b TU Dresden, Institut für Akustik und SprachkommunikationThe quality of a loudspeaker or other electro-acoustical systems is testedat the end of the assembling line by comparing the transfer behavior,parameters and other objective characteristics of the device undertest with a functional golden reference unit using defined PASS/FAIL limits.Process control requires information about the physical cause ofthe issues to initiate effective steps in time and to keep the number ofdefective units produced minimal. Visual inspection and manual defectanalysis is time consuming and requires an experienced operator whois familiar with the typical pattern of the defects occurring on the particularloudspeaker system. An interesting alternative is the introduction of