The paper describes the acoustical design and testing of a 3250‐seat multipurpose auditorium. Among the problems discussed here is the question of what reverberation time is optimal for a hall that uses a sound‐reinforcement system to augment the direct sound. The design and performance of a sound‐reinforcement system for the hall is also described. The hall has a volume of about 800 000 ft3and a midfrequency RT of 2.3 sec when empty and 1.7 sec when full. The bass ratio is approximately 1.3. The maximum variation of the sound level over the seating area is 4.5 dB. The noise level (onCweighting) in the fully occupied hall is 42±1 dB without air conditioning and 52±1 dB with air conditioning.