Hi, thanks for the help.
I'll try it with a speaker and see what results I get.
I am still keen to actually get a reading of the values coming from the set up though, just to further my understanding of how this is working and the values that are being thrown around. Surely I need serial communication in order to write these values out to my mac though? I was trying to use Serial.print(amp) to try and get an idea of what amp (see code included above in my original post) was in order to know how to appropriately manipulate the initial amplitude value to suit my needs. I got the same values (47 49 52... all around that area) regardless of whether microphone was present or not... although I've corrected this I would still like to see these values for the purpose of fine tuning and greater understanding.
cheers,
will.