As has been said, any shooting without hearing protection will damage your hearing, one shot at a time, once it's lost, it's gone forever. Even the miniscule 22Lr generates 134dB, hearing damage starts above 85dB!! /ubbthreads/images/graemlins/frown.gif
http://www.keepandbeararms.com/information/XcIBViewItem.asp?id=2052
Table 2. SHOTGUN NOISE DATA (DECIBEL AVERAGES)
.410 Bore 28" barrel 150dB
26" barrel 150.25dB
18 " barrel 156.30dB
20 Gauge 28" barrel 152.50dB
22" barrel 154.75dB
12 Gauge 28" barrel 151.50dB
26" barrel 156.10dB
18 " barrel 161.50dB
CENTERFIRE RIFLE DATA
.223, 55GR. Commercial load 18 " barrel 155.5dB
.243 in 22" barrel 155.9dB
.30-30 in 20" barrel 156.0dB
7mm Magnum in 20" barrel 157.5dB
.308 in 24" barrel 156.2dB
.30-06 in 24" barrel 158.5dB
.30-06 in 18 " barrel 163.2dB
.375 18" barrel with muzzle brake 170 dB
CENTERFIRE PISTOL DATA
.25 ACP 155.0 dB
.32 LONG 152.4 dB
.32 ACP 153.5 dB
.380 157.7 dB
9mm 159.8 dB
.38 S&W 153.5 dB
.38 Spl 156.3 dB
.357 Magnum 164.3 dB
.41 Magnum 163.2 dB
.44 Spl 155.9 dB
.45 ACP 157.0 dB
.45 COLT 154.7 dB
Recall that sounds over 85-90 dB can lead to permanent hearing damage without hearing protection. As can be seen from Table 2, even firing a .22LR (134 dB) has the potential of causing permanent, irreversible, inner ear damage.