Currently there is no model, I'm working on developing a model. I would like to set up a method where I can correlate rock types to specific frequency distribution patterns and see if I can manage to get some repeatable results for specific hardnesses/porosity of rock types. I was thinking it might be kind of similar to voice recognition algorithms, but the rock response while breaking it is the voice I would be using as input. Any ideas?

I'm designing a program that will allow me to listen to a drilling tool as it is breaking through solid rock and monitor the frequency spectrum of the rock response through an accelerometer. I'm trying to be able to identify different rock types/properties based on frequency content while drilling.