I found a few shareware audio sampling programs as I planned to take a good look at noise made by a bow. They are rather complecated. If you do a search, you can find these programs around. They will perform complex freq analysis of fourier analysis, etc.
All you need is a microphone, laptop, and it will capture the noise. Noise amplitude alone does not tell the whole story. You want to look for length of the noise, the frequencies of the noise, etc.