Try https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode As well if possible update your sound card drivers from the Manuf. Be aware Windows 10 can and will change your hardware drivers to their own drivers. https://www.howtogeek.com/302595/how-to-stop-windows-10-from-automatically-updating-hardware-drivers/ I am looking but everything is archived and will not work for your version. Frustration at it's best. Please let us know if this solved your issue or if need further assistance.