Photo Study - And the beat goes on by Jonni

View the original image here.
This photo has great lighting and the boy has a really great pose, but what about these cool little music notes Jonni added?  How could one go about adding those music notes to their photo and make it look convincing like this photo did?
This is a great example of how to use a custom-made brush and a good layer mask effectively.  I can only assume that the "edge" of the notes on the microphone are defined by a good layer mask paired with a layer that is nothing but a pattern.  The key here is the highlights and lowlights that were kept on the notes on the microphone.  That is what gives this the realilistic look, and it could be acheived with a white layer on the right layer mode paired with another layer mask that would hide everything  but the highlight.
What do you guys think?  How would you have gone about making these edits?