Hope you at least enjoyed the game…!
Thanks for pointing that out. I can try to adjust at least the initial shimmering's volume, because I agree with you in that being potentially annoying if you're unaware. Generally speaking, though, I think it’s not a problem with the inner python music/sound channels as much as your own external settings. I also use headphones to test my games precisely for this reason, and my ears were never hurt or annoyed in any other way. A lot of people tried the game (as well as another one with the shimmering) and no one else mentioned this, so I don’t think it’s my own PC, either.
Anyway, for the rest of the game, it’s much easier to keep under control the speakers’ volume, imo. If I messed with the internal volume programming-wise, the rest of the people (including those using headphones) would probably start complaining about not being able to hear a thing...