Sparkfun makes a pretty neat arduino shield that allows high speed control of EL Wire.
I've had this one for awhile. Macetech sells a shield that give you access to sound volume on analog input pins 2 and 3 through a standard audio jack.
Stack the two together and you have yourself a pretty neat setup.
An AnalogRead(2) will give you the current volume, then it's just a matter of selectively pulsing the EL-Wire outputs.