The ornamental design for an earphone, as shown and described.
FIG.1 is a first perspective view of an earphone showing my new design;
FIG. 2 is a second perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a back view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
The broken lines shown in the drawings depict portions of the earphone in which the design is embodied that form no part of the claimed design. The break in the cable shown in broken lines in the drawings are included to show a symbolic break in length of the Connector. The appearance of any portion of the article between the break lines forms no part of the claimed design.