The ornamental design for a microphone, as shown and described.
FIG. 1 is a top, front, right perspective view of a microphone showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The microphone is shown with symbolic breaks in its length. The appearance of any portion of the article between the break lines forms no part of the claimed design. The broken line immediately adjacent to the shaded area depicts a boundary line and forms no part of the claimed design. All other broken lines in the drawing depict portions of the microphone that form no part of the claimed design.