The other night at a club we were entertained by the Lover Boy band. They were excellent and of course the music was so loud it was impossible to talk back and forth at the table. Then the music became pure noise to a number of us. My question is: Is the difference between music and noise simply based on each individual’s opinion or is there a more complex answer?
I think it’s a matter of opinion, but I distinguish between music and noise based on ability to differentiate between different instruments/sounds. If music gets so loud and muddy that I can’t tell what’s what, it’s not really music anymore. But like I said, it’s all opinion, and many people would consider that “noise” to be music too.
Music is noise that isn’t annoying. Hence, the definition of “music” is subjective.
Ironically, my declaring of subjectivity is also subjective. 
When I was younger, I always thought that “if it was too loud, you’re too old.”
Now that I’m older, I sometimes think that bands play loudly to cover up how poor their musicianship is. If it’s too loud you can’t hear the fret-work on the guitars. So loudness covers up the short-comings.
Well music is noise that has been shaped/designed/arranged in a pleasing way. That includes arrangement for pitch. If you can no longer hear pitch, then it’s noise (not my only definition of noise, but it’s a place to start).
Chrome Spot: " in a pleasing way" stumps me. I have heard some heavy metal “music” and screaming singers who do not fit your definition for a good many of us. Perhaps music may simply be applied to any sound, noise, or tone that has been shaped, designed, and arranged period…
Harley-Davidson engines are tuned to make a specific sound, so that they’re recognizable as Harleys. They’d count as music under that definition. While the sound of revving engines might be “music to my ears,” that doesn’t mean I actually consider it music. 
Okay, what I was actually trying to get at was that at a certain volume you don’t hear pitch. At that point, even well-arranged and -written music becomes noise.
I just went at it from the wrong angle.
From my experience playing in bars for 2 years, you have to turn all the other instruments up so that they’re as loud as the drums. We rarely ever mic’d the drums, so during our soundcheck we just leveled everything based on the volume of the drums. We tried cheap foam dampeners for his drumheads, but they adversely affected the sound.
So…hopefully that explains why live bands are so loud in bars.