It's partially a matter of the state of technology. The way PA systems work, a speaker cannot provide an even amount of volume to an entire room, so they
crank it to compensate so the people in the back can still have an enjoyable time at the expense of anyone unfortunate enough to be directly in front and in
close range of the speaker. Bose has a new-ish PA system that can provide equivalent volume to just about every corner of the room, but it's expensive.
Some of it's sheer laziness, like Rod H pointed out. A lot of concerts are more of a show than anything else at times; they're about that strange,
awesome synergy that arises when a band can get their crowd really into it (Symphony of the Sword is rife with
examples of this energy). Techs will sometimes get lenient/negligent with proper leveling. Granted, that's a bitch since every single concert venue has
vastly different acoustics, but still, it's their damn job. That's why sound checks exist, as well as all the fiddly knobs on the mixers and the
thousands of dollars of rack equipment.
Finally, some bands just get off on sonically assaulting their audience. Just see Manowar, the current world record holder for loudest concert at ~139 decibels (compare to the sound of a jet engine which is
140db at ~100ft).
Moral of the story: bring earplugs to every concert you go to. If the band is properly leveled, like Yes did back in the day, sweet. If not, pop in the
'plugs and enjoy the concert with %100 less hearing decay.
crank it to compensate so the people in the back can still have an enjoyable time at the expense of anyone unfortunate enough to be directly in front and in
close range of the speaker. Bose has a new-ish PA system that can provide equivalent volume to just about every corner of the room, but it's expensive.
Some of it's sheer laziness, like Rod H pointed out. A lot of concerts are more of a show than anything else at times; they're about that strange,
awesome synergy that arises when a band can get their crowd really into it (Symphony of the Sword is rife with
examples of this energy). Techs will sometimes get lenient/negligent with proper leveling. Granted, that's a bitch since every single concert venue has
vastly different acoustics, but still, it's their damn job. That's why sound checks exist, as well as all the fiddly knobs on the mixers and the
thousands of dollars of rack equipment.
Finally, some bands just get off on sonically assaulting their audience. Just see Manowar, the current world record holder for loudest concert at ~139 decibels (compare to the sound of a jet engine which is
140db at ~100ft).
Moral of the story: bring earplugs to every concert you go to. If the band is properly leveled, like Yes did back in the day, sweet. If not, pop in the
'plugs and enjoy the concert with %100 less hearing decay.