There is no sound in Firefox, but in the system the sound works.
You will have to install
pulseaudio for sound to work in Whonix-Workstation.
In Whonix-Workstation konsole, run.
sudo apt-get install pulseaudio
You may have to reboot Whonix-Workstation for the installed packages to take affect. Also make sure the sound is turned up on your host.
Searching the forum as per the Free Support Principle provides many threads on this subject. Use the information found there to assist in troubleshooting.
As I mentioned in your other thread you should not be using anything other than Tor Browser