@paladinlll, The license is CC-BY, so all you have to do is credit the artist if you use the song. Its often appreciated to ask the original author if you can use it, but just crediting the author is enough based on the license. Given the license as well, I'd say that the artist probably just wants it to be enjoyed by anyone, so simply telling the artist you're using the song and crediting the artist is probably enough for most people.

If you check Open Game Art's FAQ they even recommend to comment on a work and say you're using the work in question and where you're using it. You can provide a link to your game available for download and show how its being used. It acts as promotion for both you and the original artist, so its overall a win-win situation.

The original music here in question was posted two years ago. There's no guarantee the artist is even still around or active on Open Game Art. In this case, though, the artist has posted new things as late as September 2013, but that's not always the case.

Unless the artist makes specific attribution requirements, just providing a text file with credits for any art assets used and/or adding the song to the credits of your game should be acceptable. You can optionally link to the original work in most cases as well.

If the artist in question has specific attribution requirements, though, then you'll need to follow them.