I updated my PC to the x64-version of Firefox recently and hadn't used it until this morning for audio-related issues. I couldn't get audio at all on a streaming video, so I rechecked the OS settings and the sounds played properly. So, I re-opened Firefox, went to Settings, Privacy & Security, and then clicked on the Settings button for Autoplay. The default for all websites was set to Block Audio, so I changed that to Allow Audio and Video and then saved the changes. All's well again.
As the sole user of this PC, I know I hadn't changed any settings previously. Therefore, I'm guessing this may have been a 92.0 glitch. Consequently, I'm sharing this just in case any forum members have the same issue with this iteration of Firefox.