Audible audio keeps going even after computer goes to sleep. How do I turn it off?

I listen to audible through the browser. When I close the browser, however, the audio is still running in the background. It's not audible (ha!), but when I open the lid of my computer and login, the audio is there at the very bottom of the login screen. It's messing everything up! In order to wake up the computer, I now MUST hit ctrl-alt-delete or it just beeps at me. How do I get rid of this audio? I tried turning bluetooth off thinking it might think I'm still connected, but that didn't work.