A self-adjusting implantable cochlear implant system (46) includes an implant portion (50) and an external portion (53). The system provides a device and a way to objectively determine selected psychophysical parameters, such as stimulation threshold, comfort level and loudness resolution, used by the implant portion, which includes an implantable cochlear stimulator (ICS), as it carries out its stimulation function. The input to the system is an electrical stimulation. The outputs of the system include a middle ear reflex (MER) and evoked potentials, such as a compound action potential (CAP) along the auditory/cerebral pathways, both of which are sensed using objective measurement techniques and tools. In accordance with one embodiment, the adjustment process uses the MER for determining a coarse threshold value, and then (using such coarse threshold value as a starting point) uses evoked potentials to determine a more precise or fine threshold value, thereby zeroing in on a desired threshold. Such zeroing-in method is preferably carried out using implanted circuitry (e.g., included as part of the ICS), which implanted circuitry uses an implanted middle ear electrode (54) and a cochlear electrode (56), along with appropriate amplification (58, 64), filtering (60, 66) and processing circuitry (62, 68, 67), to respectively determine the MER response and evoked potentials. Another embodiment uses the presence or absence of the MER to adjust the intensity of electrical stimulation continuously and automatically, thereby relieving the patient from having to perform slow and tedious manual adjustments of the loudness control of a speech processor used with the ICS.
SELF-ADJUSTING COCHLEAR IMPLANT SYSTEM