Setting up acoustics for large stadiums, whether enclosed or open-air, poses challenges to the designers working on the sound reinforcement systems. Since the area covered is huge, they present several problems, apart from the size of acoustic installation. Excessive reverberation, echoes, sound absorption by air, reduced speech intelligibility, refraction and synchronization of video boards with the sound reinforcement systems are some of the other challenges faced by the technicians.
Speech intelligibility can be effectively achieved by using a distributed sound system with seats positioned not more than 80 ft from the nearest loudspeaker. Reverberation in these large stadiums may sum up to 20%, where low frequency reverberation times get longer. Sound absorbers like SonaSpray fc acoustic decorative finish can be applied to the face of walls to correct the stadium acoustics.
The open air stadiums have an advantage of reduced reverberations since sound dissipates into air and thus provides better speech intelligibility. Echoes need to be considered as well and can be reduced by treating the building surfaces. Echo-producing surfaces can be angled towards surfaces like fiberglass or other porous materials that are designed to absorb sound.
Stadiums witness moments of high excitement and thus face the problem of crowd noise. These typically range between 95 to 105 dB and may also touch 110 dB. For such conditions, the sound system should be at least 10 db louder for better intelligibility. But if the crowd gets louder than 115 db, it isn’t practical to use sound systems to produce intelligible sound. Thus, stadium acoustics play a major role in helping the fans enjoy the game.