It is the test microphone, beyerdynamic (Beyerdynamic) MM1, Beringda ECM8000, superlux (superlux) ECM999/ECM888, AUDIX TM1 and so on the brand, but also need to have a table with phantom power external sound card and test software is generally used SmaartLive (SIA) used to test speakers The SMAARTLive (SIA) software is used to test the frequency response curve, phase, and sensitivity of the speakers.
Hope to help you, personal opinion