So I thought I'd share, I might have found one of the easiest/cheapest sound sensors for Arduino. (If anyone knows a cheaper/easier one I'd like to hear about it).
Before I found it, I was having all sorts of trouble simply finding a way to hook up a microphone to arduino for a sound trigger with adjustable threshold. Granted I am very new to all this stuff, so its been like a crash course for me, and much confusion along the way. I spent hours searching all over these forums, all over the web. Some people did indeed have an easy method using a guitar amp, or tape recorder, however I wanted to find a way to do it myself without relying on such a device (and not have to carry a guitar amp around). Others pointed me in the way of rather expensive premade amps, envelope followers, etc. I tried making my own amp with a LM386 chip, and making a rectifier to follow it (both of which I was completely unfamiliar with beforehand), but didn't seem to have much luck, it seemed to only detect very loud noises. Hours and research and frustration trying to do what I feel should be the simple task of hooking up a mic to arduino to detect sound levels, I was just about to order the cheapest "arduino sound sensor" I could find, one of these...http://cgi.ebay.com/Sound-Sensor-Module-Arduino-Sensor-Shield-PIC-MCU-/160523026320?pt=LH_DefaultDomain_0&hash=item255feaff90
....when I just stumbled upon one of these....http://cgi.ebay.com/Mini-Hidden-Spy-CCTV-Microphone-Mic-12V-CCTV-System-/160525859430?pt=LH_DefaultDomain_0&hash=item2560163a66
....It said in the description "can be direct connected to listening device, no amplifer is needed". Well luckily, I just happened to already own one in my parts bin, that I had bought awhile ago for about $2.50 shipped. Although I haven't pulled the shrink tube all the way off to look, it feels like its almost the identical type circuit board as that cheap arduino sound sensor. I chopped and stripped the cords to find a red, black, and yellow wire. I hooked them up to the arduino put a diode along on the input (not sure if its even necessary, but had seen other people using diodes, so I just did it), and so far it seems to work fine.
I put it in the serial monitor and with no sound I get a value of about 460. With sound the value fluctuates up and down (I had a 100ms delay between each print of the serial monitor, so i'm sure its fluxuating a lot more than I am actually seeing). In any case I was able to adjust the threshold to be able to pick up all sorts of levels of noises, even as quiet as me rubbing my fingers together near the mic.
Just thought I'd share in case anyone else is struggling doing the same thing. If anyone knows any improvements, or better (but still just as cheap), ways to do it, let me know.