On Sunday night, presumably during the 49ers' first offensive series, the fans at CenturyLink Field will attempt to set a Guinness World Record for the loudest crowd roar. It will not be an easy task.
The first obstacle is breaking the record itself. It's currently 131.76 dbA (an adjusted metric that measures how the noise actually sounds to human ears), set two years ago by 53,000 fans of Turkish soccer side Galatasaray.
While the Seahawks will have the attendance advantage, the lack of organization could be a problem. The Turkish attempt was organized by the team, with an on-field prompt to go nuts. The Seattle attempt is entirely independent, organized by fan group Volume 12. There will be no prompts on the field or the scoreboard.
The Seahawks claim the loudest crowd noise measurement at CenturyLink Field is 112 decibels, which is not the same as 112 dbA, but still a long way shy of the record.
The second obstacle is making sure the measurement is "official"—or at least accepted by Guinness. It's not an easy process. The hapless Flyers learned this when they tried to set the record for most people watching paint dry, but failed to even alert Guinness.
Volume 12 had to apply before even attempting the record. They were approved back in July. The detailed guidelines they received specify the rules:
- The sound level produced must be measured on a Class 1 precision measuring noise level meter, whatever that is.
- The microphone must be positioned five feet above the ground. The microphone must be at least 2.5 meters (8.2 feet) from the nearest fan.
- In-stadium music and piped-in crowd noise are not allowed.
Guinness will have a judge on hand to witness the attempt, flown out at Volume 12's expense. They'll also need a professional on hand to take the measurements.
For Volume 12, that meant hiring Bill Stewart, a sound engineer and partner at SSA Acoustics in Seattle.
He’s bringing two such devices, each about the size of a laptop, and each worth about $20,000. Out of the device comes a short metal tube that has a tiny and really, really expensive microphone.
Stewart says he’ll use two measuring devices because even a separation of a few feet can make a four- or five- decibel difference.
And, says Stewart, he expects a crowd roar to last maybe 30 seconds, although the peak noise will last perhaps seven seconds.
So it will be a little nuts on Sunday, even without the national TV audience and the latest iteration of what's currently the NFL's best rivalry. But to keep things from getting too out of hand, Seattle will have undercover officers wearing 49ers jerseys in the stadium.