Note: A speaker icon to mute audio in a tab is missing on tabs with Flash content if you are running Flash Player 20.0.0.235. Update your Flash installation to the latest version to remedy the issue.

Depending on the version of the Firefox web browser from Mozilla you use, it may conveniently display a speaker icon in a browser tab as a sound indicator when audio is playing in that tab. If the sound is unwanted, there is no need to mute your entire system sound by tapping the Mute button on your keyboard, or by clicking the Speakers icon in your system tray. You may simply mute the sound originating from that particular tab by doing the following:

   
  • When the audio indicator is present in a Firefox tab, single-click on the speaker icon in the tab itself to mute audio in that tab. You may also right-click on the tab, and select Mute Tab from the right-click menu.
          
  • With the tab muted, the audio indicator is modified with a diagonal strike-through. To unmute audio in the tab, single-click on the speaker icon, or right-click on the tab and choose Unmute Tab from the right-click menu.
          

The option to Mute and Unmute tabs is present in the right-click menu regardless if there is audio playing or not. If you select to mute a tab where no audio is playing, and no audio indicator is present, the mute icon still displays in the tab. This is handy to preemptively mute the audio in a tab. It is important to note that a tab remains muted even when you change locations within that tab. Keep an eye on the audio indicator if you expect to hear audio, but don’t. It may be that a tab you muted has remained muted as you navigate to another location.