Measuring short duration noises

I'm trying to find a way to measure very small differences in metal-to-metal noises that amount to "ticks" of less than one second duration. The sounds are quite similar when heard by the human ear, but I'm convinced in some cases there are variances.

The "ticks" are presently being picked up via a magnetic contact microphone in much the same way a microphone pickup would work with a guitar. They get amplified by a very low end amplifier and are audible via a headset or speakers.

Can anyone tell me how to measure/differentiate such small and short duration noises?

Thanks.

Ken Dunckel

kendunckel@aol.com