Chromeのタブについている小さなアイコンで、そのタブが実際に音をだしているかどうか判別できるようになるかもしれません(THE NEXT WEB)。


Audio indicator in each tab

Basically a throbber animation that cycles over a number of
frames on a bitmap. Currently only 6 frames, which is too little
but good enough for testing.

Note that the logic should make it so that the audio indicator
is low on the priority. That is, if the tab is recording or broadcasting and
playing sounds that should show instead of the audio animation.

以上、Chroniumの Issueの記述でした。