в вашем обработчике нажатий кнопок:
protected function click_Button(e:MouseEvent):void {
(e.currentTarget as DisplayObject).visible=false;
var sound:SoundChannel = yourSound.play(0, 1);
sound.addEventListener(Event.SOUND_COMPLETE, onSoundComplete);
}
protected function onSoundComplete(e:Event):void {
yourButton.visible = true;
(e.currentTarget as EventDispatcher).removeEventListener(Event.SOUND_COMPLETE, onSoundComplete);
}