It was loud. The loudest of course, was during the national anthem, recorded at a steady level of 116 decibels, then jumped to 122 decibels after "the rockets' red glare". That is the equivalent of a shotgun going off next to your head or a jet engine revving to maximum. 122 dB is louder than many outdoor football stadiums and near the pain threshold of 125 dBs. The loudest recordable sound, a sonic boom, is registered at 194 dBs. The loudest ever recorded at an NFL game was 119 dBs at Kansas City's Arrowhead Stadium in 1996. The loudest at an NCAA stadium was 121 dBs at Death Valley in Baton Rouge, LA during an Louisiana State game in 1991.
During the game, Hossa's goal was recorded at 113 dBs, Eager's was at 112 dBs. The end buzzer was recorded at 112 dBs as well. Those readings are equivalent of standing next to a gas powered lawn mower.
So yeah, it's loud as hell. Keep it up Hawks fans!