Audio File Research for silverlight

I am creating a silverlight 4 game and I want to know which audio format to use for the game sounds. I am looking for a good balance between sound quality and file size. I am creating a Math Bubble game (very basic game), so the sound does not have to be the same as that of the latest PC games. For this project you must suggest the best audio format and provide a little sample audio file for me to test to see if silverlight supports audio format. You must continue suggesting audio formats until we find a good format that silverlight supports. I know mp3 is a good format but I was wondering whether there isn't perhaps an even smaller format?