A method and system for automatically configuring a medical device that is at least partially implanted in a human recipient and that includes a transducer arranged to stimulate a physiological system of the recipient, such as a middle-ear implant for instance. The energy level of a signal provided to drive the transducer is progressively increased until there is a threshold electrical change indicative of a threshold change in impedance of the transducer. In the context of a middle-ear implant, for instance, the threshold electrical change indicative of the threshold change in impedance of the transducer may be indicative of the acoustic reflex. The energy level of the signal at that point is then used as a basis to set an operational parameter of the medical device, such as a comfort-level of the middle-ear implant for instance.