Google landed a pretty cool feature in Chrome Stable recently which indicates where audio comes from in the browser. While it may not be cool for users who open and close tabs one by one only, it can be a godsend for users who use session restore to bring dozens of tabs back to life, and users who open lots of tabs regularly in the browser.
The noise indicator was part of other versions of Google Chrome before it landed in the stable build. Chrome displays icons, different ones for audio, webcam and casting to TV, that you can use to quickly identify the noise source.
There are other ways to deal with that, such as muting the volume of the web browser completely, or going through each tab one by one until you find the noise maker, but they are not as efficient as what Google has implemented.
Firefox and audio indicators
If you look over to Mozilla and Firefox, you notice that the browser does not support audio notifications in tabs. Why is that you may ask.
If you check Bugzilla, you notice that bug 486262 addresses the issue. It was filed in March 2009 and suggested to add visual indicators as to which tab is causing sound in the Firefox web browser.
So, Mozilla had this planned or at least on the radar since before Firefox 3.1 was released. Yep, that is a long time ago in a galaxy far far away, or so it seems.
Why has not this been implemented? The core reason why is that Mozilla has no control over plug-in contents in this regard.
Google Chrome uses an internal version of Adobe Flash which Google can use to determine when Flash is being used for audio playback.
Mozilla does not have that luxury. While it is working on a patch to display indicators when HTML5 is being used for audio playback, it cannot do anything about plug-in contents on its own.
Well, the organization has a couple of options, but all will take time to implement. First, it could try to convince Adobe to provide audio indicators that the browser can use for the feature. This would be the fastest option if Adobe agrees to that.
It could alternatively put all chips on Shumway, the Flash-alternative that it is developing right now. Since it has full control over Shumway, it could use it to display audio indicators if Shumway is being used.
Mozilla is at a clear disadvantage here in regards to audio indicators in the browser. While Flash will lose some of its appeal in the coming years, it is unlikely that it will vanish completely in that time.
There is no clear and direct solution for Mozilla, and while it may make sense to talk to Adobe to find out if the company is willing to provide Mozilla with the information it needs -- which probably requires changes made to the Flash code -- it may still take quite some time before this gets implemented.
Maybe someone will come up with a workaround for that, for instance by simply checking if plugins are currently loaded on web pages to indicate that, as it would help narrow down which tabs to check for audio sources.