gloom humming in background music

whats up with this new humming sound covering the background music? Every few seconds theres this humming sound that lasts for a few seconds, raises in volume slowly up to a point thats louder than the actual music then goes slowly back down to repeat again later.

This keeps going on and on, it's in every map, delve, hideout, town, etc. Started since this patch. Changing character doesnt remove it. Quitting the game does remove it, but at some point later while playing starts again. This didnt happen before last patch. Im in standard league.

so i just noticed it now triggering during a Vaal side area in a map, but it continued to persist when i finished it just as described earlier. It still happens and only quitting the game stops it. This didnt happen previous patch.

doesnt trigger from every side vaal area, but thats definitely the source. It's from "ambient" sound settings, doesnt go off when i turn back on the sound, it even persists on the character selection screen, and the only way to remove the bug is to quit and relaunch.