Monophasic stimulation pulses with alternating polarity and extraordinary polarity changes

摘要

Arrangements are described for generating electrode stimulation signals to electrode contacts in an implanted cochlear implant electrode array. Electrode stimulation signals are a sequence of monophasic stimulation pulses varying in polarity between positive polarity and negative polarity with successive pulses separated in time by an interpulse interval sufficient for neural response. Accumulated charge imbalance and charge imbalance polarity are calculated for each electrode contact after each stimulation pulse. For each electrode contact a stimulation pulse has the same polarity as an immediately preceding stimulation pulse for that electrode contact only when the charge imbalance polarity has opposite polarity from the immediately preceding stimulation pulse for that electrode contact, and the accumulated charge imbalance exceeds a defined charge imbalance threshold value. Otherwise, each stimulation pulse has the opposite polarity as the immediately preceding stimulation pulse for that electrode contact.