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 side elevational view thereof, the opposite side is a mirror image;
FIG. 3 is a front elevational view of the embodiment shown in FIG. 1.
FIG. 4 is a bottom elevational view of the embodiment shown in FIG. 1.
FIG. 5 is a top elevational view of the embodiment shown in FIG. 1; and,
FIG. 6 is a rear elevational view thereof.
The broken lines in FIG. 1 form no part of the claimed design while the broken lines in FIG. 6 define the bounds of the claimed design and form no part thereof.