Psychophysical tests are administered to cochlear implant (CI) users to determine a spectral modulation transfer function (SMTF), smallest detectable spectral contrast as a function of spectral modulation frequency, for each individual CI user. The determined SMTF for individual CI user is compared against a SMTF of a normal hearing person to determine the specific enhancements needed. A profile of spectral enhancement achievable with variation of filter parameters, sigma and maximum that best fits the needed enhancements for the individual CI user is selected. Based on the corresponding sigma and maximum selected, a sound processing strategy is adjusted to provide customized spectral contrast enhancement for the individual CI user. The sound processing strategy implemented includes an outer hair cell model.