so in conclusion does it need to interface with other software also? matlab?? i'm thought its a simple project. 

Right now it can only detects patterns of knocks and illuminate the green LED it if the pattern is correct. I don't want to detect pattern...
I'm trying to compare sound.. can someone help me?

okay.. i have remove other topic...

Can anybody help me on developing a sensor instrument that can differentiate a dull ( hollow sound ) and a solid sound of a material  when we light knock on it.. Right now i'm using piezeo speaker as the analog sensor...Before start ,I will test (light knock) on a good sample materials ( solid sound ) to record as the reference sound..  It can detect the sound but it cannot differentiate the sound.. is it due to the programming or what?