In order to play a sound from the library you can use the following simple AS3 code:

var snd:Beep = new Beep();
snd.play();

You must also assign your sound clip a class name by right clicking the sound in the library and checking the export for ActionScript option. In the example above the class name was set to “Beep”.

The default base class  is set to “Sound”, allowing inheritance of methods from the Sound Class.

as3 play sound