The proposal that a sound change is occurring in Korean stops was evidenced in this study through identification experiments on Korean stops. Perceptual weight of acoustic correlates to Korean stop manner contrast [VOT (Voice Onset Time), H1-H2 (amplitude difference between the first and second harmonics), and F0 (Fundamental frequency)] was examined with re-synthesized /$t^ha$/, /ta/, and /$t^*a$/ syllables for younger and older Seoul speakers of Korean. For the identification of the aspirated and lenis stops, F0 cue weight relative to VOT was greater for the younger listeners than the older listeners. For H1-H2 cue weight, the two listener groups were more or less the same. These findings were parallel to the production differences found in the earlier work of the author. Combined with production differences, these perception differences between younger and older generations of Seoul speakers suggested that there are generational differences in the phonetic targets of Korean aspirated and lenis stops and such differences are realized in the perception of the stops.