Motion Picture Theaters

Although motion pictures include speech and music, the design of movie theaters is driven by speech intelligibility considerations rather than by the need to provide reverberant support for unamplified music. The theater itself is an important link in the production chain since a film, as a mass-produced entertainment medium, is most effective if it is viewed in a controlled environment that yields the same auditory experience for every patron. Not all movie theaters are the same but they should be designed to achieve a consistent listening environment.

Figure 17.26 SMPTE Standard Reverberation Time vs Room Volume (SMPTE, 1989)

Figure 17.26 SMPTE Standard Reverberation Time vs Room Volume (SMPTE, 1989)

ROOM VOLUME, Thousands of cubic feet

Reverberation Times

By and large, motion picture theaters are built to be acoustically dead, with absorptive material on virtually every surface except the floor, which must be washable. Ceilings are dark-colored acoustical tile and the side and rear walls are covered with minimum 1" thick cloth wrapped fiberglass panels or heavy pleated drapes. Curved rear walls should include 6" of fiberglass batt behind the panels to reduce focusing.

Recommended standards have been issued by SMPTE (Society of Motion Picture and Television Engineers) and by THX, a private company founded by George Lucas, on the preferred background noise levels, reverberation times, and sound system equalization curves. Motion picture theaters are designed to an NC 30 background-noise level and to the reverberation times shown in Fig. 17.26. THX recommends a minimum transmission loss rating (STC 65) for walls separating theaters, as well as a list of approved sound system components.

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