We claim the ornamental design for a speaker, as shown and described.
FIG. 1 is a front perspective view of a speaker showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left-side view thereof;
FIG. 5 is a right-side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof;
FIG. 8 is a partial cross-sectional view thereof taken through the vertical center in FIG. 4, showing the cross-section of the transparent upper case and the horn portion; and,
FIG. 9 is an enlarged view of the encircled portion shown in FIG. 1.
The short dash-dash broken lines in the figures show portions of the speaker which form no part of the claimed design.
The dot-dot-dash broken lines encircling portions of the claimed design that are illustrated in enlargements form no part of the claimed design.