Heavy metal exposure contributes to auditory dysfunction, yet subgroup-specific risks remain understudied. Using NHANES 2017–March 2020 data, this study evaluated associations between urine and blood heavy metals and hearing loss among children aged 6–19. Among 2,673 included participants, subgroup analysis revealed that Hispanic children exhibited a significant association between urine mercury levels and all hearing-loss classifications: low-frequency, high-frequency, speech-frequency, and any-frequency hearing loss (p < 0.05 for all). This relationship was not observed in non-Hispanic children, nor with blood mercury levels. Findings may reflect chronic exposure differences, socioeconomic factors, or combined effects of multiple metals. Limitations include small subgroup sample size and missing audiometry or metal-testing data in some participants. Further analysis using elastic-net regression and additional sociodemographic variables is planned to clarify interacting risk factors and identify vulnerable groups.