Three Radio or Clock (Or whatever you called it), has to be activated to play the hidden song.
First Location, Canal District. This item is inside the building called Ruby Rabbit. To open it, you need to be in beast mode and look up on the balcony and grapple it. Once you are inside, go down on the second level and zap the electric box to activate the door. Go back to a human, then on the first level. Turn left and you will see the item on the top of the table.
Second Location, Footlight District. Head towards to the train station all the way to the top level and turn right and you will see a bench where the item is located.
Third Location, Waterfront District. Go all the way to the dock where you will see a boxing gym. To open this, same as we did on the first location. Do beast mode and melee the door. Once this is open, Head over the second level and the item will be on the table.
Note: You will hear a chime if you did it correctly. This can be done in any order and can be played once in every gameplay.