Abstract: A mechanical stimulator for evoking a hearing percept by directly generating waves of fluid motion of fluid in a recipient's scala tympani. The stimulator comprises a sound processing unit configured to process a received sound signal; and an implantable stimulation arrangement, comprising: an actuator configured to receive electrical signals representing the processed sound signal and configured to vibrate in response to the electrical signals, a stapes prosthesis having first and second ends, the first end having a surface configured to be positioned abutting the round window in the recipient's cochlea, and wherein the first end surface is substantially orthogonal to a longitudinal axis extending through the actuator, an elongate rod extending longitudinally from the actuator connecting the actuator to the stapes prosthesis such that vibration of the actuator results in waves of fluid motion in a recipient's scala tympani that evoke a hearing percept of the received sound signal.