Mozilla is working on identifying Firefox tabs that are currently playing audio. The feature will show an icon if a tab is making sounds and let the user mute the playback.
This has been available as browser add-ons and extensions for a while, but users want it built into the browser. Back in February 2013, we first heard audio indicators were coming to Chrome. Indeed, the feature arrived in January 2014 with the launch of Chrome 32. Now it