Fig. 3. American multi-purpose concert hall/theatre with a contained stage where the envelope of the hall and the shell provide all required source and listening area acoustic design criteria. --- detroit" ford auditorium .A,..,. r" to f::::? Fig. 4. t::::?~ ~~ - T "T * I ~ American multi-purpose concert hall/theatre where the envelope of the stagehouse and the auditorium provide some of the required source and listening area acoustic design criteria and an articulating inner system of shell and forestage canopy provides the remainder. savannah CiViC center Continued on Page 38. 26 ~ THEATRE DESIGN AND TECHNOLOGY FEBRUARY. 1974