Abstract: A hearing aid includes an implantable microphone, signal-processing amplifier, battery, and microactuator. An electrical signal from the microphone is amplified and processed by the amplifier before being applied to the microactuator. The microactuator is adapted for implantation in a subject at a location from which it may mechanically create vibrations in the perilymph fluid within a subject's inner ear. A transducer of the microactuator is preferably a thin circular disk, 2 to 8 mils thick, of stress-biased PLZT. Disks of this stress-biased PLZT material can be mounted as drumheads in various different ways, preferably in conjunction with a flexible diaphragm, to small threaded metal tubes, e.g. 1.4 mm in diameter and 2.0 mm long. These tubes may be implanted into a fenestration formed through the promontory adjacent to the oval window of a subject's inner ear.