Just came across this site with noise pressure levels for different calibers. According to them, an 18" 12ga shotgun is twice as loud as a 28". FreeHearingTest.com - Gunfire Noise Levels In fact, the 28" 12ga is easier on the ears than any centerfire pistol. Does this make a good case to ditch the slightly more maneuverable and tacticool 18" HD gun in favor of a bird gun? "Shotgun noise averaged slightly more that 150dB. This is approximately 14dB beyond the threshold of pain, and more than sufficient to cause sudden hearing loss with complications."