71 Chapter 5. Microphones, P.A. Systems, and Troubleshooting Microphones, a.k.a. mikes, are devices used to turn an acoustic signal, like a voice or a drum, into an electronic signal that can be recorded or amplified. PA systems allow the microphone to be heard. We'll also add in a little here on repairing stuff. Because part of being a D.I.Y. musician is taking care of your own gear. Different microphones have different pickup patterns. This refers to how they pick up sound. A cardioid (a.k.a. unidirectional) pattern is heart shaped; it picks up most sensitively from the front and the sides, but not much from behind at all. They are good for live miking of vocals.