This study investigated the optimal listening level for a woman's voice reproduced by self-checkout systems in convenience stores and supermarkets for Japanese and Chinese men and women, to examine gender and cultural differences in optimum listening levels for voice stimuli. As background noise, pink noise was reproduced at 45 dB, 55 dB, 65 dB, and 75 dB. The experimental results revealed that Chinese women set the optimal listening level significantly lower than Japanese women, regardless of background noise conditions. There was no significant difference in the optimal listening level between Japanese men and Chinese men. Gender differences were statistically significant only between Japanese men and women, with Japanese women tending to set higher optimum listening levels than Japanese men. This tendency differed from the results obtained in previous studies.