A combined set (71) comprising a vibration actuator and an implantable device to be used as an artificial fenestrum implantable in a bony wall (25) of an inner ear, said device comprising a frame (32) made of a biocompatible material and provided to be applied at least partially in said bony wall, said frame being provided with a wall part formed by a membrane (27) forming a barrier with a perilymph of said inner ear when applied in said bony wall, said membrane being provided to form together with said frame an interface with said inner ear, said interface being provided for energy transfer towards and from said inner ear, said membrane being electrically dissociated from said vibration actuator and provided for receiving vibration energy from said vibration actuator.