AES Section Meeting Reports

Central German - January 20, 2006

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A joint meeting of the Central German Section and the DEGA German Society of Acoustics was held at the University of Technology, Businesss and Design in Wismar, North Germany. Professor Wollensak welcomed an audience of 35 members and guests on behalf of Wismar University, shich has become a lesding center of architectural design and building construction, offering several excellent gradduate programs.
E.-Jo. Voelker, who teaches room acoustics and sound reinforcement systems both at Wismar and the Technical University of Sarmstadt, talked about how sound reinforcement systems have to fulfill many strict requirements including the Sound System for Emergency Purposes, EN ISO 60849. Professor Voelker underlindes the importande of following such acoustical guidelines — the so-called "allgemein anerkannte Regeln der Technik". In consulting engineers fail to incorporate these requirements, building defects may occur, he said. For example, if room acoustics are not sufficiently regarded, the result may be over-noisy workplaces, restaurants, and punlic spaces. He talked about how to configure the best sound system for a particular space and whether or not it is possible to achieve a natural soundfield ba implementing many loudspeakers throughout a room. His general advice to the audience was to follow the rules of electroacoustical design in order to achieve goog speech intelligibility and a satisfying environment for music.
Teuber then talked about sound systems designed for emergency purposes, espesially those systems that meet the strong requirements of obtaining a certain intelligibility of words with the standard Speech Transmission Indesx of STI = 0.7. Teuber demonstrated how to measure the effectiveness of a system using a simple test using locatomes (meaningless syllables). Ambient noise must be low and the signal high in order for these systems to work effectively, he said. Sound systems for emergensy purposes must be checked continuously for security reasons. The EN ISO 60849:2002 is, therefor, a challenge for consulting engineers who must deal with room acoustics and electroacoustics.
Michael Sommer concluded the session with a demonstration of special techniques that may be used to handle reverberation time, umpulse responses, noise levels, and measurements of STI.

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