"The radio emissions were discovered by radio and plasma wave detectors on board the Cassini spacecraft as it passed over Saturn's rings during its arrival at the planet in July 2004."
NASA says: "Shit mang, we don't know what it be."
Personally, I don't really buy the alien speech thing. Just because it sounds weird, it doesn't mean it's aliens. We don't even know what aliens would really sound like, except for what's in our imaginations, and we've only been exploring small areas of space for a few years, so how can we know for sure what this is? Obviously we don't.
It's still pretty creepy to listen to, though. Like listening to EVP or Beatles albums backwards.