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?
media.block-play-until-visible
inabout:config
can be set totrue
. This should prevent autoplay for background tabs.