var tabla:Sound = new Sound();
 
tabla_btn.addEventListener("click", hearTabla);
 
// tabla_btn.addEventListener(MouseEvent.CLICK, hearTabla);  would be better
//                            ----------------                than "click"

var reqTabla:URLRequest = new URLRequest("tabla.mp3");
 
tabla.load(reqTabla);
  
function hearTabla(eventObj:Object):void 
{
    tabla.play();
}