Not playing sound on IE

Hello Everyone!

I'm making a start page of a Website. Its simple, you click on "Entrar no Site" that means "Enter the Website" on my language xD, and the camera shoot, with a flash effect and a sound. But in IE the sound does not play! Someone knows how to fix it?

Here the page > abcrede.com.br/PAINELAR

And here de File > mediafire.com/download.php

Your server sends .m4a files as text/plain. It should send them as audio/mp4. Make sure your MIME types are set up correctly.

Thanks for the help xD