The mic has a switch on it that imposes a hardware high-pass filter to counterbalance the proximity effect you get from being close to it. Since the mic is a ca

The mic has a switch on it that imposes a hardware high-pass filter to counterbalance the proximity effect you get from being close to it. Since the mic is a cardioid mic (directional sound pickup) it would normally pick up a great deal of extra bass due to the geometry of the cardioid capsule (radio announcer sound, big and deep and bassy). The switch lets you take away that bassiness and the pop filter prevents the mic from going 'THUMP' when you say 'P' into it, and the combination of these things gives you that super-present, 'NPR interview' sound.