for music, I've tried lots of different genres and have settled on progressive house mixes as a good focusing background sound. It's complex enough to occupy me without any jarring changes or vocals that cause me to pay active attention to it. There's quite a few playlists on YouTube and I just run random ones each day, this is the one that's currently playing for me: https://www.youtube.com/watch?v=w23j_nspEy0