The ornamental design for a lanternspeaker, as shown and described.
FIG. 1 is a perspective view of a lantern speaker of the present disclosure;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a side view thereof;
FIG. 5 is a top view thereof; and,
FIG. 6 is a bottom view thereof.
The broken lines in the figures illustrate the portions of the design that form no part of the claimed design.
The dot-dash broken lines immediately adjacent to the claimed areas in the views represent the boundaries of the design and form no part thereof. None of the broken lines form any part of the claimed design.