The ornamental design for a microphone, as shown and described.
FIG. 1 is a front perspective view of a microphone, showing my new design;
FIG. 2 is a rear perspective view of the microphone;
FIG. 3 is a front elevational view of the microphone;
FIG. 4 is a rear elevational view of the microphone;
FIG. 5 is a top plan view of the microphone;
FIG. 6 is a bottom plan view of the microphone;
FIG. 7 is a left side elevational view of the microphone;
FIG. 8 is a right side elevational view of the microphone; and,
FIG. 9 is a perspective view of the microphone, shown in an environment of use.
The broken line showing of the headset in FIG. 9 depicts environment and forms no part of the claimed design. All other broken lines depict portions of the microphone that form no part of the claimed design.