Headphone

The design is the visual features of a headphone shown in the drawings, whether those features are features of shape, pattern, configuration or ornament, or are a combination of any of these features, with non-design portions of the article shown with stippled lines. The “skull” logo forms no part of the design. In the drawings: Fig. 1 is a rear perspective view of a headphone embodying the design; Fig. 2 is a front perspective view thereof; Fig. 3 is a front elevation view thereof; Fig. 4 is a left side elevation view thereof; Fig. 5 is a rear elevation view thereof; Fig. 6 is a right side elevation view thereof; Fig. 7 is a top plan view thereof; Fig. 8 is a bottom plan view thereof; and Fig. 9 is an exploded perspective view thereof. Drawings showing the design are included.