chrome.api* method to know if a tab has audio
Is there a way in a chrome extension to know if a tab is currently playing an audio content (from Flash, <audio>, <video>, Web Audio API or any other way (Aka, when the "speaker" is in the tab title).
Chrome Tabs seems to have no informations about that.
There's none for that right now but you may want to file a feature request at http://crbug.com/new to let the chromium team know about your interest for it.
Yes of course: since Chrome 45 you can use the audible Tab property.