Among other things, a stimulation strategy can be customized for a cochlear implant implanted in an individual by testing at least a pair of electrodes selected from an array of electrodes associated with the cochlear implant. Testing the at least a pair of electrodes includes applying a first stimulation to the at least a pair of electrodes using a first pair of pulse trains that are in phase, and applying a second stimulation to the at least a pair of electrodes using a second pair of pulse trains that are out of phase. A determination is made on whether the at least a pair of electrodes stimulate the same neural population based on a sensitivity of the individual to detect a perceived difference between the two pairs of pulse trains. The one or more electrodes of the array of electrodes are selectively stimulated based on the determination.