Life Safety, Part 2: From Noise to Nice: The Evolution of Speech Intelligibility in Stadium Sound

Modern venues have come a long way since the tinny, echoing audio of the mid 20th century

Through the 1940s, 1950s, and 1960s, large sports venues and ballparks typically deployed two-way, horn-loaded speakers designed for a narrow-bandwidth frequency range focused on human speech, notched more or less around 1 kHz. Anyone who has ever seen the 1942 sports tear-jerker The Pride of the Yankees has heard these types of systems: as Gary Cooper, portraying legendary New York Yankees first baseman Lou Gehrig, delivered his valediction that, despite his ALS diagnosis, today I consider myself the luckiest man on the face of the earth, the words literally echoed throughout the iconic stadium.

In that era, the same venue PA systems were used for all sonic purposes, from announcements to life safety and music. (At the time, the Hammond Organ was the pre-DJ era's instrument of choice; the first one was installed on April 26, 1941, at Wrigley Field and connected to the stadium's public-address system.)

Click here for Life Safety, Part 1: The Other Venue Sound System

The inflection point in sound-system design for these venues came, appropriately, in 1965, when the Beatles played the MLB Mets' Shea Stadium in Queens, NY. The crowd noise, which reached a reported 131 dB, overwhelmed Shea's tinny in-house public-address system - the same tube-powered horn speakers normally used by announcers to read the batting lineup - and the additional columnar speakers the show brought in, resulting in music that was completely drowned out by 55,000 screaming fans.

Since then, demand for better sound quality has steadily increased, in recent decades paralleling better audio for sports' broadcasts. In addition to broadband frequency-reproduction capability, for music and sound effects, stadium and arena sound systems now also achieve high levels of speech intelligibility, the benchmark for life-safety systems in particular, charged as they are with not only alerting crowds but also directing them.

Achieving that involved measurements and modeling. Audio engineers measure clarity on a 0-1 scale using standardized metrics like Speech Transmission Index (STI/STIPA). Values above 0.5 are acceptable, and scores above 0.75 are considered excellent. Major stadiums aim for minimum scores of 0.5 to 0.55.

Because today's stadiums and arenas often serve as concert venues, their audio systems have improved and are more able to serve life-safety purposes.For system design, computer-modeled simulations predict sound reflections, delays, and coverage gaps before physical installation, followed by installation of line arrays and column-array speakers that project sound precisely onto seating areas and away from reflective walls or open air. The arrays and speakers are further tuned by DSP, including automatic gain control (AGC), feedback suppression, and equalization (EQ) to compensate for changing crowd sizes and weather.

These aspects of sound-system design apply to both entertainment and life-safety sound systems, with the latter also having system-override and self-testing capabilities, which ensure that they're ready when needed. But the life-safety systems also have an advanced college degree: some type of official certification.

What certification adds is accountability, says Ross Brett, global application lead, sports facilities, L-Acoustics, which recently announced its products' certification to Europe's EN 54-16 and EN 54-24 standards. Amplifier and loudspeaker circuits are monitored, faults are reported, and there is a backup path, so the system assures you constantly that it is healthy rather than being assumed healthy. In Europe, you inherit that by specifying certified products. In the U.S., you can build [in] the same integrity, but proving it falls to the designer and to the authority having jurisdiction, rather than to the product certificate.

LINK:	https://www.sportsvideo.org/2026/10/07/life-safety-part-2-from-noise-t...
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