Dude thank you thank you been stuck here for a while. The Abiotic Factor guide is out of date and would rather have you try to climb the bookshelves and jump onto the broken handrail, but shooting the composer and ducking under the shelf is so much easier!
You can reach slightly higher by jump crouching. It was a staple of old FPS games from the Half Life era. Basically jump up and at the apex of the jump, crouch mid air.
