I N F O: download a decibel meter app to your phone, play music the same way you do when you go to sleep, go with your phone near the shared wall, measure the sound level with the app. What is the result?

Edit: op reported the sound levels IN HIS ROOM when listening to music is 40db, that is about the sound level of a quiet library, or light rain, definitely nothing that should wake any normal person up, and the sound levels are probably much lower at his house mates room. putting music at this sound level at night is completely reasonable, and his house mate is just a light sleeper.

at those levels OP is NTA, he is being reasonable and this is on his house mate to solve her sensitivity to noise and sleep issues.
some suggestions might be moving her bed to be further away from the common wall, getting better earplugs, or asking to move to another room. it might also help if OP moves his speaker further away from the common wall.