In a hearing aid (26) that can be inserted into the ear canal (12) of a patient, comprising an actuator (31) effecting a mechanical stimulation of the tympanic membrane (14), the actuator (31) comprises an inner surface (32) associated with the tympanic membrane (14) and an outer surface (42) associated with the ear canal (12) and is configured as an areal disk actuator, whose deformation stimulates the tympanic membrane (14) by areal deformation. On the actuator (31) at a distance from the outer surface (42) a cover plate (43) is arranged which together with the outer surface (42) delimits a preferably lenticular cavity (48).