Yeah, I understand that it is done on purpose, but I think it's overdone a bit.
You can still have the jumpscares work, even if your ambient sounds were a louder, such that people don't dial up the volume before encountering jumpscares. Also, FYI set_volume() has a range from 0.0 to 1.0 and larger values will be clipped at 1.0.
Just my two cents, because I think it doesn't live up to an otherwise excellent game with beautiful art style, with subtle horror and and an interesting mechanic.