Firefox has an option to mute a tab. Particularly useful when a misbehaved website opened in a background tab suddenly starts playing a video with sound.

Is it possible to tell Firefox to open new tabs with muted sound by default, so that tabs will only play sound after I explicitly give permission to do so?

  • 4
    Alternatively, media.block-play-until-visible in about:config can be set to true. This should prevent autoplay for background tabs.
    – JC2k8
    Jul 19, 2016 at 9:32

3 Answers 3


New tabs are typically given focus immediately when they are created, so this won't help in that case. Only new tabs opened in the background would be muted this way by default until you make one of them active.

Firefox 55.0.2 (64-bit) in Ubuntu 16.04:

about:config [I accept the risk!]

Search: media.block-autoplay-until-in-foreground [Double click the search result line to toggle the value between false and true.]

Reference: https://www.ghacks.net/2016/11/14/firefox-51-blocks-automatic-audio-playback-in-non-active-tabs/


Is it possible to tell Firefox to open new tabs with muted sound by default?

You can use the Mute Tab add-on:

About this Add-on

Current tab context menu items:

  1. Mute/Unmute All Tabs

Current add-on settings:

  1. Auto-mute new tabs
  2. Mute Tab while holding a certain key

Source Mute Tab


Go to about:config and enter mute in the search field. Double click dom.audiochannel.mutedByDefault to flip it from false to true. Restart Firefox.

  • 1
    It doesn't let me to manually un-mute a tab after changing this property
    – Andrei LED
    Feb 3, 2017 at 8:42
  • 3
    This answer is misleading, untrue, useless and probably also untested. See bugzilla.mozilla.org/show_bug.cgi?id=1301099 - "In this case, dom.audiochannel.mutedByDefault does not have any relation to what the mute button does. It's an internal thing for the (originally b2g-targeted) Browser API" + "tell people to not set random pref" Feb 7, 2017 at 11:33

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