Youtube has some great videos with sound.
Jim
Assuming you mean for model trains and a possible selection for you locomotives?
It was on this forum or the ATLAS forum where one of the responders gave this address out. It is the updated ESU or LokSound. It is great. There is a gray box next to the pucture of the locomotive and you click one time on it. Make sure you have you speaker turned up a ttle so you do not miss the many small sounds.
Http://www.esu.eu/index.php?id=339
Hope this helps, Chris