An ossicular replacement prosthesis (ORP) (10) for coupling a first point toa second point in the middle ear of a patient, to replace all or part of the ossicularchain. The ORP comprises a coupling having a variable configuration for accountingfor pressure differentials, said coupling comprising a fluid filled chamber(28, 14) having two relatively moveable portions (12, 22) for varying the configurationof the coupling. The coupling comprises unsealed means constituting leak meansand flowpath means for permitting displacement of the fluid (30). The relativemovement of the relatively moveable portions is controlled by the movement ofthe fluid in said chamber. The chamber is configured to restrict the movementof the fluid such that relative movement of the moveable portions is permittedin response to quasi-static changes in pressure, and is substantially preventedin response to vibrational changes corresponding to sound frequencies.
