Ill break your sound. (c) Lennart Poettering
Since Mozilla is not smart enough to support both ALSA and Pulseaudio and rejects any suggestions to fix this (WONTFIX), regular ALSA users like you are forced to install this piece of PSHSHS.
This repository is your chance to be free of that!
You may also get some lulz.
... Well, just google "firefox breaks alsa".
Click here to continue.
You can switch your language here, download language pack for your country: https://addons.mozilla.org/ru/firefox/language-tools/