A system comprising: a memory (302, 1106) storing instructions (306, 1112); and a processor (304, 1104) communicatively coupled to the memory and configured to execute the instructions to: direct a cochlear implant to apply electrical stimulation by way of a first electrode disposed on an electrode lead that is being inserted into a cochlea of a recipient; direct the cochlear implant to record, while the electrical stimulation is being applied by way of the first electrode, a differential voltage signal representative of a differential voltage between a second electrode and a third electrode both disposed on the electrode lead, the second and third electrodes different than the first electrode; determine, while the differential voltage signal is being recorded, that a signall characteristic of the differential voltage signal changes by at least a threshold amount; and determine, based on the signal characteristic changing by at least the threshold amount, that a distal end of the electrode lead is positioned within a threshold distance of a basal turn of the cochlea; wherein the signal characteristic comprises a slope associated with the differential voltage signal, wherein the processor is further configured to execute the instructions to generate an impedance signal based on the differential voltage signal, and wherein the slope corresponds to the impedance signal. a memory (302, 1106) storing instructions (306, 1112); and a processor (304, 1104) communicatively coupled to the memory and configured to execute the instructions to: direct a cochlear implant to apply electrical stimulation by way of a first electrode disposed on an electrode lead that is being inserted into a cochlea of a recipient; direct the cochlear implant to record, while the electrical stimulation is being applied by way of the first electrode, a differential voltage signal representative of a differential voltage between a second electrode and a third electrode both disposed on the electrode lead, the second and third electrodes different than the first electrode; determine, while the differential voltage signal is being recorded, that a signall characteristic of the differential voltage signal changes by at least a threshold amount; and determine, based on the signal characteristic changing by at least the threshold amount, that a distal end of the electrode lead is positioned within a threshold distance of a basal turn of the cochlea; direct a cochlear implant to apply electrical stimulation by way of a first electrode disposed on an electrode lead that is being inserted into a cochlea of a recipient; direct the cochlear implant to record, while the electrical stimulation is being applied by way of the first electrode, a differential voltage signal representative of a differential voltage between a second electrode and a third electrode both disposed on the electrode lead, the second and third electrodes different than the first electrode; determine, while the differential voltage signal is being recorded, that a signall characteristic of the differential voltage signal changes by at least a threshold amount; and determine, based on the signal characteristic changing by at least the threshold amount, that a distal end of the electrode lead is positioned within a threshold distance of a basal turn of the cochlea; wherein the signal characteristic comprises a slope associated with the differential voltage signal, wherein the processor is further configured to execute the instructions to generate an impedance signal based on the differential voltage signal, and wherein the slope corresponds to the impedance signal.