How the NFL tried to make fake crowd noise real, from a raucous Kansas City to more boos in Philadelphia

Sports leagues around the world have wrestled with this question as games in empty or near-empty stadiums became the bargain of playing through a pandemic. Beginning with European soccer this summer, fans have, depending on their view, either been treated to the technical wizardry of piped-in crowd noise or bombarded with gratingly fake stadium sounds that rob sports of their authenticity.

Caputo, though, had an idea for how to inject some authenticity into the inauthentic. For several years, he and his crew have been collecting sounds from the crowds at every NFL stadium with the intent to add it to various productions from the NFL. With hundreds of clips at his disposal, he wondered whether they might be the answer.

“We had it catalogued,” Caputo said. “And the need came along: What are we going to do without fans?”

Caputo didn’t know how to deploy them until he turned to Robert Brock, director of education at the Conservatory of Recording Arts and Sciences in Tempe, Ariz. For decades, Brock has trained audio technicians and engineers, with many recent students going on to work on video games. In 2006, Brock began working with a new software program called Wwise, which helps bring video game series such as Assassin’s Creed to aural life.

If Caputo’s work at NFL Films work is linear — he adds sound to a finished video product after the fact — what Brock could do with Wwise was something more advanced: adding scripted audio reactions to unpredictable events in real time.

They went to work. Caputo and his team combed through the NFL’s audio clips and isolated crowd noise from every stadium, filtering out the public address announcer and music. Brock categorized them, sorting them into positive and negative reactions from the home crowd with four intensity settings for each — low, medium, high and peak.

For instance: a four-yard run by Saquon Barkley is a low positive reaction from New York Giants fans. A first down pass by Aaron Rodgers in Green Bay probably would earn a medium positive response. But if Tom Brady throws a game-winning touchdown pass to Rob Gronkowski in Tampa Bay, cue the peak setting. There are also four different settings for the crowd noise that builds before every play, denoted by levels 1, 2, 3 and “raucous,” which would be used, for example, on fourth and one with the home team’s defense on the field in the fourth quarter.

There are the clips for boos, too, which Caputo said would not be deployed for poor play but only for an obviously bad call. Certain stadium soundtracks picked up more boos than others, he said. (One of those stadiums, yes, was Philadelphia’s.) There is even separate sound for when a player suffers an injury.

“We don’t want inappropriate crowd sounds if there’s a guy down,” Brock said. “So those are just very neutral ambient elements.”

Armed with Brock’s cache of sounds, audio engineers in each stadium are tasked with inputting the game situation into Wwise as it happens. The program sorts through the hundreds of clips to deliver the audio to the broadcast.

Stadium-wide chants, such as “Go, Pack, Go” in Green Bay, have been edited out, though there are some individual cheers from fans that will be heard by viewers. “There’s a lady in Los Angeles who says, ‘Let’s go, Rams!’ ” Caputo said. “I know that’s in there.”

Mostly, though, the differences from stadium to stadium are subtle. The sound made by cheering fans wearing winter coats in Green Bay has a different tone than fans cheering in warmer weather in Miami, Brock said. And the “crowd noise” for games played in Seattle and Kansas City, home to two of the league’s noisiest fan bases, are notably louder.

Most fans probably will never notice the difference in any individual game. But, Caputo and Brock said, over the course of a full season the tonal differences are important and will serve viewers better than generic crowd noise that might be found in a video game.

“If you’re watching multiple games in a day and you’re doing that over the course of a season and every single game has the exact same ambient noise, then your ear would know something isn’t right,” Brock said.

Added Caputo: “Is the net of all the work we did to make all 32 stadiums individual and authentic going [to match] what it reads to every fan? Probably not. But we did it because we could.”