audio synced leds to massive speaker box

so I am as green as grass when it comes to electronics and programming. and I made this awesome portable speaker that is running off a 12v battery. I have 2, 12inch, 12v, red led strips in front of both speakers and instead of a simple on and off toggle switch that they are both wired to. I also already have an arduino micro and 3.5mm jack on a breadboard. I was wondering if it is possible to us an in-line slitter in the audio to the arduino to control a relay to turn the leds on and off in sync with the music like an music organ, but it is all on or off? if it is, how would I go about programming the arduino micro. i also attached photos.

Yes - but not a relay, a transistor instead.
Logic level, Low Rds, N-channel MOSFET:

Sensing the audio: browse the forum for threads on using MSGEQ7

You going to put some insulation in there also to improve the sound?
http://www.parts-express.com/acousta-stuf-polyfill-speaker-cabinet-sound-damping-material-1-lb-bag--260-317