Same here ... I had been having problems with it being too loud, now I can't hear anything and have not made any adjustments to the volume.
1.118.ba04d96153 (08.01.2018 14:41), Achaeus (127556), zz1, en_US, WIN 28,0,0,126, Windows 7, Firefox/52.0, 1920x887, DirectX9Ex (Baseline Extended) (336 MB VRAM)