Why has the "currently playing" symbol disappeared in itunes 11.0.4?

The little loudspeaker icon that appears to the left of the "name" column has disappeared from my itunes 11.0.4. I can't find a button in Preferences or a selection under "View" that would get it back. Does anyone know how to make it reappear? (I know I can look up at the info bar to see the title, but it's a lot faster to just glance at the name column.) Thanks!