project guidance (newbie)

beatid:
The product idea is a headphone ie like the apple kind that can recognise music and change color accordingly to the beat

Anything is possible no doubt, but personally I wouldn't be attempting it, and I've dabbled in electronics most of my life, and programmed almost all of it.

You have a number of issues, "recognise music" is one of them, and fitting inside a headphone is another.

However there is a possibility, Google:

arduino fft spectrum analyzer

There are quite a few posts about that, and basically people have indeed done some sort of coloured reaction to music. YouTube videos even. That might help you down your path.