The ornamental design for a loudspeaker, as shown and described.
FIG. 1 is a front elevational view of a loudspeaker showing my new design,
the rear and sides being identical;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof; and
FIG. 4 is a front elevational view of a second embodiment of the
loudspeaker illustrated in FIG. 1, the rear and sides being identical and
the top and bottom being identical to FIGS. 2 and 3 respectively.