Loud Sports Venues Challenge PA Systems’ Ability To Keep Up

While fans are watching the battle between teams on the field or the court, another contest is increasingly being played out around them: the PA system is sometimes battling the stadium itself.

Stadium and arena architectural design has included a mission to amplify sound for decades, part of the natural immersiveness that makes attending mass sports events attractive. However, in recent years, that mission has moved up in the hierarchy to become absolutely strategic, making the venue itself a massive megaphone for crowd noise and used to sonically obfuscate the visiting team’s verbal communications.

Seattle’s CenturyLink Field, which recorded an ear-splitting 136.6 dB last year, has become the poster child for this effect. The stadium’s two massive canopies, at either end of the bowl, not only protect fans from weather and sun but also act at natural amplifiers for crowd noise, with their parabolic shapes focusing the noise onto the field.

As stadiums get louder, venue PA systems have to keep up, in part to keep the narrative moving forward, in the form of announcements, and also to conform to life-safety regulations. In fact, a new JBL VLA sound system was installed at Kansas City’s Arrowhead stadium last year precisely because the previous system — which was only three years old and not functionally obsolete by any means — was simply unable to get above the crowd noise. At the same time, however, the NFL has rules in place about when and how loud audio content can be played through PA systems in the league’s stadiums.

New Products Help
These often conflicting requirements can create challenges for systems designers, who are using a combination of newer sound-system and acoustical products and techniques to try to satisfy all parties. “In  recent years, PA systems have become louder, but they’ve also become better able to be more precisely focused,” says Brian Elwell, VP/senior consultant at Acoustic Dimensions’ Dallas office.

Aiming sound systems away from reflective surfaces and directly toward seating areas is more predictable, thanks to improved beam-steering technologies. But techniques can also be deployed: for example, covering arena ceilings with absorptive material above a suspended acoustical “cloud” designed to reflect and amplify sound downward helps keep ambient crowd noise naturally amplified while reducing the reverberation that can impair PA announcement intelligibility.

Designers rarely achieve that delicate balance between ambient crowd volume and PA intelligibility on the first try. Rather, systems now need more tweaking and fine-tuning than ever. Elwell says designers are increasingly rely on computerized modeling to predict the nature, intensity, and direction of reflections throughout a venue. But even with more-precise tools, he emphasizes, experience is just as critical: “You can’t rely on the models alone; you need to have a history of knowing how real a model may or may not be in the real world.”

Brute Force
To a large extent, brute force has become one solution. A new Danley sound system installed at Penn State’s Beaver Stadium, which holds more than 106,000 fans, can reach more than 125 dB down to 80 Hz at peak power. Texas A&M’s Kyle Field, which seats more than 80,000, now has deployed JBL VLA components, which are usually used in line-array configurations, in four-speaker clusters as a distributed system capable of hitting close to 130 dB. The sound system in Vancouver’s Canadian Football venue BC Place features 160 four-channel Lab Gruppen amplifiers cumulatively putting out nearly 1.8 million W.

“It’s stunning the amount of power we can throw at stadiums,” says Tim Mazur, regional sales manager for Clair Brothers Audio Systems, which did the installations at all three of those venues. “It’s not the only tool we have to counter loud ambient stadiums, but, as overhangs like the canopy at CenturyLink become more common, it’s one way the PA system design can cut through.”

Lee Buckalew, audio systems designer at TSI Global, says that sheer volume coupled with the ability to more precisely steer sound onto seats and away from reflective surfaces has become the one-two punch for many loud stadiums. TSI recently re-specified speaker components for the St. Louis Rams’ Edward Jones Dome from JBL VT4888 enclosures to VT4889 models, with improved beam steerability. “Using more-precise steering lets you accomplish the same result using fewer boxes, which also can reduce system costs,” he explains.

In fact, the ability to put sound more exactly where it’s wanted — and keep it away from where it’s not — could change the dynamics of the manufacturing side of the business. “People are actively looking for that capability now, and it’s opening up the market to new possible suppliers,” he says, noting Martin Audio’s MLA system that he says may get new traction in the U.S. sports market.

The phenomenon of stadium acoustics vs. sound-system performance isn’t limited to the U.S. WSDG principal John Storyk notes that louder PA systems were part of the designs called for in three Rio de Janeiro World Cup venues on which his firm did acoustical consulting last year. He cites FIFA specifications as helping keep a useful balance between acoustics and powered sound in soccer venues globally.

“Those venues tend to be less concerned about sound quality for music, which U.S. sports venues have to be for multi-use applications, than about intelligibility for life safety,” he says. “But soccer stadiums are huge and can get insanely loud, and execution of designs can vary pretty widely country to country. So having standards that are the same no matter where you are is a good thing.”

The arms race between PA systems and stadium acoustics isn’t likely to wind down anytime soon, now that strategic cheering has become a fan-engagement practice in many venues. So, as stadiums get acoustically louder, PA systems are trying to follow suit.

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