"Play" or "start" icon from Tango Project Since version 0.8.90 Tango Project icons are Public Domain: Tango Project FAQ tango sign symbol Tango Media Start
"Stop" icon from Tango Project Since version 0.8.90 Tango Project icons are Public Domain: Tango Project FAQ tango sign symbol Tango Media Stop
"Audio card" icon from Tango Project Since version 0.8.90 Tango Project icons are Public Domain: Tango Project FAQ tango icon audio Tango Audio Card