I am currently trying to incorporate the sensing of tool wear as part of my research, which is an investigation into an experimental manufacturing process that is probably most similar to milling. I have already been making use of force data, but would like to utilize acoustic data as well (there are a number of papers on detecting tool wear in milling which record the acoustic signals and then transform the data using FFTs). I would like to do something similar to this, but am unsure of what is the best type of microphone to purchase. Based on previous experiments with a very crude standard-issue microphone, I think I need something that is capable of capturing high frequencies. Does anyone have any recommendations with regard to products or vendors? I have been looking at piezoelectrics, intensity acoustic sensors, and ultrasonics. My knowledge of acoustic sensing is very limited, so any help you could offer is much appreciated!