but if you have any examples on audio projects, I'd love to try some out!
I don't appreciate being sent to a site that Bombards you with pop up windows about being a lucky winner.Why use two batteries?If you have to use two then you need a common ground between the two.Did you not get the point about Instructables being crap and you should only read them if you are smarter than the author, which is not hard. Never use that site to try and learn stuff, it is just sooooo bad.
You have not got a common ground between your battery and the Arduino. Wire th black wire of the battery to ground of the Arduino.
Still does't work
Yes but what are you playing into it?