On the early sketches, the Hawks Nest bleachers were on the south end of the stadium, and the field-level end-zone suites were designed to invite Seahawks players to jump in among the fans, creating a Seattle version of the Lambeau Leap.

But planners quickly decided the Hawks Nest would better frame the view of the Seattle skyline on the north.

For unknown reasons, Seahawks touchdown scorers have not developed the habit of executing Hawk Hops over the short divider near the north end zone.

The noise created by the 12th Man fans and captured and reflected by the stadium configuration, well, that has more than met expectations.

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“(Seahawks owner) Paul Allen challenged us to generate a home-field advantage,” said David Murphy, original project director on what would become CenturyLink Field, which opened in 2002.

A recent test revealed a noise reading of 137.6 decibels during a Seahawks home game. That’s in the range between a pneumatic jackhammer (130 dBs) and a jet engine at 100 feet (140 dBs).

Saints coach Sean Payton is well-aware of the environment, having felt the measurable seismic activity when running back Marshawn Lynch scored the touchdown that beat New Orleans in January 2011, the last time they met in Seattle in the postseason.

So he is not interested in hearing about record decibel readings as his team prepares to play the Seahawks on Saturday at CenturyLink Field in an NFC divisional-playoff game.

“It’s kind of like August down here in New Orleans,” Payton said this week. “At some point, it’s as hot as can be, and we don’t need to know the exact temperature.”

But in the spirit of public service, Payton and the Saints should be reminded that the National Institute for Occupational Safety and Health warns of exposure to noise above 115 dBs for more than 15 minutes.

Welcome to an afternoon at CenturyLink Field: Home to 68,000 pneumatic jackhammers. New York Giants offensive lineman Shaun O’Hara, November 2005

O’Hara referenced the Nov. 27, 2005, game when frenzied fans discombobulated the Giants’ offense into 11 false starts and caused then-Seahawks coach Mike Holmgren to present the game ball to the 12th Man fans the next day.

Re-examine the effect of those 11 false starts. The Seahawks surely needed them in a 24-21 overtime victory. A loss in that game, and they would have finished 12-4 instead of 13-3, and the Giants also would have been 12-4 with a head-to-head win over the Seahawks to own the tiebreaker for NFC home-field rights.

Since 2005, Seahawks opponents in Seattle have committed a league-high 141 false starts — their faulty communication reputed to be caused by the intrusion of crowd noise.

Their advantage at CenturyLink the past two seasons has led to NFL-best figures in home record (15-1), home winning margin (17 points per game), home takeaways (41) and home turnover margin (+25).

Excluding Super Bowl XL, the Seahawks are 7-2 in home playoff games and 2-9 on the road. But they’ve won five in a row at home since starting their Super Bowl run in the 2005 season.

Seahawks linebackers coach Ken Norton Jr. has played and coached in 20 postseason games, more than anybody on the Seahawks’ roster or staff. He is the only player in NFL history to win three consecutive Super Bowls (two with the Dallas Cowboys and one with the San Francisco 49ers).

“Our 12th Man is unlike anything I’ve ever known,” Norton said when asked to compare his experience in NFL venues since the late 1980s. “There is no comparison: CenturyLink is far above and beyond anything I’ve ever experienced. Not to take away anything from Cowboys Stadium, which they’ve blown up, or Candlestick, which they’re about to blow up, but nothing’s even close to CenturyLink.

“Nothing compares to that energy and excitement.”

Norton cited great fans in Kansas City as well as the captured noise in some indoor arenas, but he contended the difference in Seattle is the expectation of the fans.

“They come here expecting to set records,” Norton said. “They expect to have an impact on the game with the false starts and keeping quarterbacks from making their checks. They absolutely know they are a part of this team.”

But, really? A part of the team?

“Absolutely, that’s for real,” Norton said. “The noise factor, and how that works into our pass rush ... that’s something we work into our game plan.” David Murphy on the way the roof canopies reflect the crowd noise back to the field

Then with the architectural firm Ellerbe Becket, Murphy spent his first day working on the Seahawks stadium project taking a tour of Husky Stadium. It was led by one of Allen’s Vulcan Inc. employees — former Washington quarterback Damon Huard.

Allen told Murphy how much he loved the experience of football games in the open air at Husky Stadium, where the cantilevered roofs cover most of the seats and, to some extent, reverberate the crowd noise. So the visit to Husky Stadium informed Murphy.

But the Kingdome, despite its flaws, also passed down influences to its SoDo successor — particularly in the way its design connected the fans to the action.

“It’s a legacy that goes back to the Kingdome days,” Murphy said. “It was a loud building that had a pretty intimate seating bowl with fans right on top of the action. That played into the design of CenturyLink.”

There was little choice, in fact, because CenturyLink’s urban setting mandated a smaller footprint than any other in the NFL.

“We had to find ways to fit an NFL stadium in there,” Murphy said. The answer was to stack the upper deck and angle all the seats toward the field.

“People wonder why a lot of domed stadiums aren’t louder. Well, they’re designed to accommodate concerts, so they have absorbent material in the roofs,” Murphy said. “But we wanted this to stay loud, so there’s no absorbent material in our roofs, and they’re positioned and oriented so it focuses the sound back at the field.”

The 3,000 aluminum bleacher seats in the Hawks Nest were intentionally designed in anticipation of the effect of 6,000 stomping feet. The innovative addition of the Red Zone Suites in the north end zone, Murphy said, was the idea of executives Bob Whitsitt and Bert Kolde “to create another price point and make it unique ... we were looking for a place where fans could interact with the players.”

Has anyone taken that leap?

“I think the most memorable thing was Terrell Owens signing the ball,” Murphy said of the 2002 Monday night game when the San Francisco receiver autographed a touchdown ball and handed it to one of his advisers, who was occupying a suite rented by Seahawks cornerback Shawn Springs — whom he had just beaten for the score. Saints quarterback Drew Brees after New Orleans’ Dec. 2 loss at CenturyLink

Some say CenturyLink’s facing canopies resemble clamshells. That’s probably from the perspective of Northwesterners with the taste for bivalve mollusks. To outsiders, it might look like a pair of jaws or a huge Venus flytrap.

Teams have fretted about it for years, many practicing the weeks before Seattle games with loud sound tracks pumped into practice facilities.

Most alter their game plans somewhat because of the noise, going to silent snap counts or going with quicker snaps and fewer audibles. So the effect is not just in the disruption of the false starts, but also in how teams alter their scheme and mechanics.

In December, the Saints tried special ear plugs.

Coach Payton recalled how well that worked, as a miscommunication on their first offensive snap caused the play to be botched and end up in a 4-yard loss.

“That was not real smart of me,” Payton said this week. “You open the game with a play that should go left but might be able to go right ... it’s probably right after they just raised the 12th Man flag, so it’s as loud as the stadium can be.”

The reputation of Seattle’s home-field advantage has spread beyond the players, coaches and football fans. Time magazine did a feature on it in September titled: “The Science of Sound: How Seattle Got So Darn Loud.”

Well, it got so darn loud with a confluence of three factors: an exciting football team playing in front of fervent fans in a unique setting.

Seahawks cornerback Richard Sherman warned visitors how difficult it is to prepare for this dangerous combination.

“Some (opponents) blare the noise from speakers, and if you play it loud enough, it’ll somewhat simulate it,” Sherman said. “But to simulate the noise, and to simulate our personnel along with the noise and everything that comes along with it, well, that is pretty difficult.”

It is not just the sound of CenturyLink, then, but also the fury within.

HOME-FIELD ADVANTAGE

Since moving to the NFC in 2002, the Seahawks have posted the second-best home record in the conference. The top five teams:

TeamRecordPercentage

Green Bay66-29-1.693

SEATTLE66-30.688

Atlanta60-36.625

Minnesota60-36.625

Chicago59-37.615

Dave Boling: 253-597-8440 dave.boling@

@DaveBoling