That dull roar still rumbling between your ears a day later is not your imagination. It's the echo from the 49ers-Seahawks game Sunday night, when an already notoriously loud hometown crowd outdid itself. How?

Start with CenturyLink Field, a U-shaped stadium with cantilevered roofs extending over most of the 67,000 seats in the grandstands, a configuration designed to bounce back sound. Then throw in some fans presumably hopped up on espresso and, thanks to a later starting time, some more who stopped at Safeco Field on the way over to quaff 24-oz. beers offered through a promotion at a mere $4.50 each.

Next, mix in their dislike for a nasty NFC West rival and especially coach Jim Harbaugh, who smacked the Washington Huskies every chance he got when he was at Stanford and has been tormenting Seahawks coach Pete Carroll ever since.

Finally, throw in that early, unexpected lead and -- voila! -- a near-perfect sound storm.

Just know it could have been worse.

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