I think this is impossible to do if the audio is being played via java/flash/etc as the plugin bypasses the browser completely. Here's a comment from the google

I think this is impossible to do if the audio is being played via java/flash/etc as the plugin bypasses the browser completely. Here's a comment from the google chrome team from a while back: http://www.reddit.com/r/IAmA/comments/gdyun/iama_we_are_three_members_of_the_google_chrome/c1mwuaa http://www.reddit.com/r/IAmA/comments/gdyun/iama_we_are_thre... It should however be possible for webpages that use browser APIs to play audio (e.g. via HTML5).