Figure 2.

Examples of two general forms of electric stimulus that may be generated by cochlear implants. The ordinate shows current, whereas the abscissa shows time. At the top is a sequence of two biphasic pulses. Each pulse comprises two short intervals during which a constant current is delivered to the active electrodes. The current has equal magnitude in the two phases, but opposite directions. The phases may be separated by a brief time during which no current flows. The lower panel shows a so-called “analog” stimulus, in which the electrode current varies continuously in time.