David Dixon played 11 NFL seasons for the Vikings, but the former guard was not ready to block a 66,913-fan purple wave before the 2019 season finale against the Bears while sounding the Gjallarhorn in the upper levels of U.S. Bank Stadium.

Sounding the Gjallarhorn — signaling an awakening of the gods in Norse mythology — has been a Vikings pregame tradition since 2007, when the team hired a Bloomington music shop to make the first version.

But due to pandemic restrictions limiting crowds, Dixon could become the last until possibly 2021 to summon the Vikings and lead a full stadium in the Skol chant.

"That was nerve-racking," Dixon recalled this month. "Because you have all eyes on you. Playing was a different thing because I knew how to play."

The electric atmosphere inside U.S. Bank Stadium has amplified to a 120.2 decibel level (during the "Minneapolis Miracle" win vs. the Saints in the 2017 playoffs), and the Gjallarhorn's unmistakable sound has become an integral part of the Vikings fan experience.

The horn is known around the NFL as a sparkplug. Former Lions cornerback Darius Slay admitted an appreciation for the centerpiece last season, according to the Detroit Free Press.

"I actually love the horn," Slay said in September. "Like, I love when they say, 'Skol!' See, that is gangsta. I love that. They by far got the best stadium in the NFL."

Practice is the only scenario to which former Vikings defensive end Brian Robison could equate a future NFL season without intense crowd noise. Robison, who sounded the Gjallarhorn before the Vikings' prime-time game against the Packers in December, said the extreme emotions of Sundays and an empty building would be an odd mix.

"It's going to be awkward," Robison said. "We get zoned in to what's going on — you don't always hear the fans or them being there, but they are such a huge aspect of the game at the same time."

Time will tell what atmosphere is allowed at 2020 NFL games, but the Gjallarhorn (pronounced yahl-lahr-hawrn) has weathered storms before.

Norse mythology states the Gjallarhorn, from Old Icelandic equivalents of the English words "yell" and "horn," is equipped to the god Heimdallr — a watchman on a bridge over the river Gjöll, the root for the first syllable of Gjallarhorn, according to the American Swedish Institute. The horn sounds when enemies near.

Only below-zero temperatures have cracked the Gjallarhorn. It shattered before the Vikings' January 2016 playoff loss to the Seahawks at TCF Bank Stadium where the air dipped to minus-6 degrees. Todd Johnson, creator of the team's first and second versions and a general manager at Groth Music, rushed in a replacement.

A much larger Gjallarhorn has since been installed in the north corner of U.S. Bank Stadium. From a perch in the upper level, prominent former players, coaches, celebrities and societal figures have sounded the start of every home game since the 2016 season. The moment can resonate for former players.

"You start to roll through all those guys that have done that over the years," Robison said. "Randy Moss and John Randle. You realize you're part of that club. It's pretty special."