Model Testing of Auditoriums

This report first reviews the history of model tests as an aid to the designing of auditoriums, beginning in 1913 with W. C. Sabine's spark photography and eventuating (1934-) with the more sophisticated Spandock three-dimensional models scaled down to 1:10 and 1:5. At UCLA. we use first two-dimensional optical model tests (as developed by R. W. Leonard in 1954), which are expedient for determining approximately optimal shapes in plan and sections, followed, when deemed necessary, by tests of three-dimensional models that range in scale from 1:1 to 1:4 for critical (often repeated) segments of walls and ceiling, and down to 1:24 for the walls, floor, and ceiling, which can be examined separately, and also as progressively assembled into the complete model of the auditorium. Examples will be presented of procedures and findings in connection with the acoustical designing of several multipurpose auditoriums, a theater in the round (240°) with thrust stage, and an experimental shell for symphonic and concert music. Acoustical model testing reveals diffraction effects and echoes (or their absence), and helps in the designing of auditoriums that optimize early reflections, diffusion, reverberation, and sound-level distribution.