The ornamental design for a hearingaid, as shown and described.
FIG. 1 is a side view of a hearing aid of my design;
FIG. 2 is another side view of the hearing aid of my design;
FIG. 3 is a perspective view of the hearing aid of my design;
FIG. 4 is another perspective view of the hearing aid of my design;
FIG. 5 is another perspective view of the hearing aid of my design;
FIG. 6 is another perspective view of the hearing aid of my design;
FIG. 7 is another side view of the hearing aid of my design; and,
FIG. 8 is another perspective view of the hearing aid of my design.
The broken lines in the drawing views are included for the purpose of illustrating a portion of the hearing aid that forms no part of the claimed design.