Yes, simple. Download a program called "Lamexp" and perform a method called "compression" to reduce the file size. The greater the compression, the smaller the size, and the lesser the quality of the song. You can compress a song by reducing it's "bit rate".
You can experiment with different "bit rates" to find a good balance between file size and quality. I managed to fit a 3 minute song in my map with a file size of 800KB. The song's quality was ok to listen to.
I suggest you google sound file compression if you need any further help.