I knew about OP's problem for years with discord's piece of shit webapp being the most egregious offender. For my system the sound falls into a low power state and there's an audible pop/click when something wakes it up. Even with the tab silenced and all notifications turned off it would still periodically do this. Other sites that used WebRTC had same problem but not as frequent. I think I worked around the issue eventually by disabling the automatic low power state at the expense of some additional battery consumption.