sentences:  Its popularity and classic design has resulted in the 77-DX becoming an iconic microphone, used by broadcasters and media personalities such as Edward R. Murrow, David Letterman and Larry King.The directionality of the 77-DX is variable.A rotating backshutter on the acoustic labyrinth, controlled by a screwdriver-operated slot at the rear of the microphone, allows the user to vary the microphone's pattern from omnidirectional in the fully closed position, to cardioid, to figure-8 (bidirectional) in the fully open position.