Right, Release notes of version 52 say:

On Linux, Firefox now requires PulseAudio to play sound and no longer plays sound directly with ALSA.

Mozilla dropped support for ALSA and is now requiring Linux users to have installed the PulseAudio library to support audio playback inside Firefox.

See also:

• bug 1247056 - Require PulseAudio to play sound on Linux

(please do not comment in bug reports
https://bugzilla.mozilla.org/page.cgi?id=etiquette.html)

I see. Thank you for the info! That's not a very Linux-supporting decision. :( Firefox has been working without too much hassle for so many years!! Still, if this is for real I will without doubt switch all my installations to something else. Wouldn't touch Pulse with a ten foot pole.

Hello, I am disappointed. I have no sound since upgrading. I upgraded to version 54.0.1 (64-bit). I had version 52 (64-bit) which worked with no issues. This is the Linux version of Firefox.

I keep getting an alert telling me to install PulseAudio. I already have PulseAudio. Even so, I re-installed PulseAudio. That did nothing. Thanks in advance. B'H.

Sincerely FirefoxUser001

Glus said

I see. Thank you for the info! That's not a very Linux-supporting decision. :( Firefox has been working without too much hassle for so many years!! Still, if this is for real I will without doubt switch all my installations to something else. Wouldn't touch Pulse with a ten foot pole.

In any case, I solved the issue. I uninstalled Firefox. I found a copy of the outdated version of Firefox and it works like a charm!.. If you do this, be sure to set your preferences to disable the automatic updates!!! These updates are stupid and they do NOT work. B'H.