Bart Hubbuch

Bart Hubbuch

NFL

49ers return to Northwest to face home-strong Seahawks

Conspiracy theorists might question if it’s truly organic, but the potency of the noise level at Seattle’s CenturyLink Field can’t be denied.

It’s been measured at an ear-splitting 112 decibels and is such a difference-maker for the Seahawks that — even in an NFC West matchup awash in compelling storylines — sound continues to be the prime topic going into their showdown with the hated 49ers on Sunday.

As if Seattle’s “12th Man” crowd wasn’t loud enough, the team also is purporting to enter the Guinness Book of World Records for loudest stadium noise by reaching 132 decibels in this game (a level that fun-killing audio experts later said actually is impossible for 65,000 people).

The prospect of even more noise than usual has to send a chill into the 49ers, considering one of the only blemishes on their Colin Kaepernick-led run to the Super Bowl the second half of last season was a 42-13, Week 16 obliteration in Seattle.

When you combine that wall of noise with reigning NFL Offensive Rookie of the Year Russell Wilson and a ferocious defense, it’s little wonder Seattle went a spotless 8-0 at home last season.

Not only is San Francisco the Seahawks’ new rival in a suddenly tough and reborn division, but this also is something of a revenge game for Seattle because the 49ers are the most recent team to win at CenturyLink Field, escaping with a 19-17 victory in Week 16 of the 2011 season.

Jim Harbaugh’s team had just six penalties in their road loss to Seattle last year, but the crowd noise still caused San Francisco’s offense communication problems. Harbaugh continues to have a healthy respect for it.

“They do a very good job of bringing a lot of noise up there,” Harbaugh said this week. “Not to compare it to anywhere else, but it should be [ranked] right up there.”

The Giants famously committed 11 false-start penalties against the Seahawks in a game in 2005, prompting then-GM Ernie Accorsi to voice suspicions to the league that Seattle was artificially pumping in noise.

Nothing was ever proven, and, despite much prodding, Harbaugh and his players refused to be lumped in with the skeptics this week, no doubt out of fear it only would make the problem worse Sunday.

Kaepernick is fearless, but even San Francisco’s unflappable young quarterback seemed a bit unnerved by the prospect of how much ringing his ears will do Sunday night.

“You have to be on top of everything that you’re doing,” Kaepernick said of playing in Seattle. “You have to try to project your voice, make sure everyone’s hearing what’s going on. You just have to be prepared.”

The noise is far from the only juicy angle in this matchup, though, with Harbaugh unsurprisingly as the root of most of the intrigue.

Not only does his prickly relationship with Seahawks coach Pete Carroll stemming from their days as Pac-12 coaching rivals never seem to get any better, but Harbaugh’s antics have turned mouthy Seattle All-Pro cornerback Richard Sherman — who played under Harbaugh at Stanford — into one of his former coach’s most vocal critics.

It’s a prime-time showdown that promises to be fun. Just be sure to bring the earplugs.

HUBBUCH’S PICK: 49ers 20, Seahawks 16.