The ornamental design for a loudspeaker, as shown and described.
FIG. 1 is a front elevational view of the loudspeaker;
FIG. 2 is a rear elevational view thereof;
FIG. 3 is a top plan view thereof, the bottom plan view being a mirror image of the top plan view;
FIG. 4 is a right elevational view thereof, the left elevational view being a mirror image of the right elevational view;
FIG. 5 is a sectional view along line 5--5 in FIG. 1; and,
FIG. 6 is a sectional view along line 5--5 in FIG. 1 when the loudspeaker is installed.
The broken line showing of FIG. 6 is for illustrative purposes only and forms no part of the claimed design.