frequency will basically be how quickly the cycles are happening and amplitude will be how big they are. anyone know how to code that?
Actually real-time processing of analog audio signals, no matter what the source of the audio signal, is a awful lot to ask of an arduino. It would involve a lot of math (FFT calcs). Not saying it's impossible, but rather very unlikely you would be able to do anything useful. Micros with built in signal processing hardware (DSP) are more suited to that kind of task.
Lefty