I am looking to find a way to monitor a mechanical objects noise frequency. The end result would be the ability to see when the sound changes. Here's my thought process: A mechanical object that is making repetitious movements, would generate a particular 'sound' or 'frequency' within a particular range, on a consistent basis. If that objects signature changes, that would indicate a change in the object creating the sound. So what type of equipment could be purchased, made, designed to facilitate capturing the 'signature/sound/frequency' I am looking for? I never got too involved with sounds/frequency so I'm not sure what terminology to use here either. Any advice on where to look, what to look for, or even the proper terminology to use would be appreciated. Thanks!