Thanks for the reply. Why isn't the arduino fast enough to simply pass audio through, reading it from an ADC and writing it directly to a DAC? Wouldn't 8 bit 22khz audio simply be a string of 8 bit numbers running along at 22khz and the arduino is running much faster at 1mhz? Or am I completely misunderstanding the issue?
And by ADC to arduino audio detection do you mean something like the piezo knock sensor idea on the playground where you're simply sensing the input go over a certain threshold? Or do you think it might be possible to turn an audio rate signal into a usable control signal?