Seattle Seahawks fullback Derrick Coleman’s ability to block out all the noise that will engulf Sunday’s NFC Championship game against the San Francisco 49ers at raucous CenturyLink Field has turned a perceived impairment into what he calls “a blessing.’’ Profoundly deaf since the age of three, Coleman didn’t pay attention to the naysayers who told him he would never realize his NFL dream. And Sunday, of all places he could have ended up, he’ll be impervious to a place known for its booming noise. “It definitely seems ironic,’’ Coleman said. “I just consider it a blessing. I’m glad I’m on this side. But even if I wasn’t and I was somewhere else and I came here, all that noise would not be a factor to me. Coleman, undrafted out of UCLA where he rushed for 765 yards and 11 touchdowns his senior season, wears hearing aids that allow him to hear “seven to eight’’ on a scale of one to 10 “on a good day.’’ Without his hearing aid, his hearing would be a “one.’’ So when he runs out of the CenturyLink tunnel Sunday, the core special teams player who has inspired his coaches and teammates by overcoming his hearing impairment won’t be rattled by the fury of the Seahawks’ trademark “12th man’’ which set a Guinness Book record this season for the league’s loudest crowd.