Stadium acoustics-design challenges and solutions

Large stadiums, whether enclosed or open-air, present many acoustical design challenges including excessive reverberation, echoes from surfaces distant from the sound system loudspeakers, sound absorption by air, refraction, difficulty achieving acceptable speech intelligibility, and synchronization of the sound reinforcement system to the video boards. This paper is an overview of how these challenges have been met in several professional sports facilities. Reverberation times for these large venues are normally underpredicted on the order of −20% by conventional methods. Low frequency reverberation times (down to 63 Hz) tend to be extremely long—about 15 s on average. A novel approach will be described to estimate these values (within a wide range of possibilities) based on in situ measurement data. It will be shown that after exhausting all possibilities of acoustical treatments, the most effective way of achieving acceptable speech intelligibility is to use a distributed sound system with no seat being more than about 80 ft from the nearest loudspeaker.