The ornamental design for a powerhearingaid, as shown and described.
FIG. 1 is a front view of the power hearing aid;
FIG. 2 is a right side view of the power hearing aid;
FIG. 3 is a bottom view of the power hearing aid;
FIG. 4 is a left side view of the power hearing aid;
FIG. 5 is a top view of the power hearing aid;
FIG. 6 is a bottom view of the power hearing aid; and,
FIG. 7 is a perspective view of the power hearing aid.
The broken lines in the drawing views are included for the purpose of illustrating portions of the power hearing aid that form no part of the claimed design.