The Short Increment Sensitivity Index (SISI test) was given with three increment magnitudes, 1.00 dB, 0.75 dB, and 0.50 dB, to a group of 24 normal hearing subjects and to a group of nine subjects with cochlear lesion hearing loss. The presence of cochlear pathology in the latter group was supported by the results of loudness balance tests of recruitment. The SISI test distinguished the cochlear pathology ear from the normal ear more consistently with the 1.00 dB increment than with either of the two smaller increment magnitudes investigated. The major conclusion of the study is that the SISI test should be continued with the 1.00 dB increment originally proposed.