Acoustic design for University of Southern California, Annenberg School of Communications, lecture hall remodel

Abstract

In 1998, the redesign of the 250-seat lecture hall at the USC Annenberg School of Communications was undertaken to update the aesthetics of the 1974 design and meet the modern functional requirements of the University. Primary uses of the hall were to be lectures, audiovisual presentations, and panel discussions. The existing fan-shaped space had a concrete ceiling, plastered concrete side walls, and a concave rear wall with a slatted wood acoustic finish. The existing reverberation time (RT60) was 0.95 s at mid-frequency, but there was a sense of over-reverberance and a lack of speech clarity. This was attributed to focusing by the curved rear wall and to excessive bass reverberation. The acoustic design targets included a modest reduction of the mid-frequency RT60, a significant reduction of the bass reverberation, and mitigation of the effects of focusing, as well as a maximum noise level of NC30 for the new HVAC system. Simple materials, including gypsum board wall linings, fabric wrapped panels, and acoustic foam in inconspicuous areas, were used to achieve cost effectiveness. Acoustics and architecture were fully integrated for efficiency of design. The project, completed in 1999, was an acoustic and architectural success. [Architectural Design by Siegal Diamond Architecture.]