A middle ear transducer arrangement is described for engaging a round window membrane of a patient cochlea. A mechanical transducer is surgically implantable into a fixed position in the round window niche of the patient cochlea adjacent to the round window membrane. A drive face on the outer surface of the transducer has a diameter less than half the diameter of the round window membrane. The fixed position of the transducer engages the drive face against a side section of the round window membrane without engaging the center point to generate an acoustic stimulation signal for perception as sound.