YouTube, Flickr, Photo Bucket, and about twelve dozen others all allow you to upload audio files.
Is the problem technical? Or is it that you want to be able to do so anonymously, without having to create an account?
If the latter, MOST of them only require a valid e-mail address. If you create that with a false name and access it via a proxy, your identity, including your IP address, physical location, etc. are safe. What you see on TV, with them identifying someone "bouncing off servers" all over the world is nothing but pure Hollywood horse hockey. That's the way it looks for normally routed traffic. That's not the way it works with proxy servers.