IEPE microphone

[SEPIDEH1991]

I want to buy microphone for fault detection of rotating machinery. but I do not know that I must buy array microphone or free field microphone.

please help me

what kind of microphone is suitable for me?

what is the difference between these kind of microphone?

[Henrik_Volkers]

Usually one would use an accelerometer ...a  solid borne sound sensor

But the type of sensor strongly relates to the use case.

We can give you hints if we better know your use case.

Or you pick up the phone and ask application engineers from Bruel&Kjaer, PCB, Kistler, Endevco.... 

There is a huge price difference between a simple accelerometer and a field microphone array 🙂

Another (not cheap but versatile) way is a laser vibrometer...