To elucidate the mechanisms responsible for deteriorated postural control in children with hearing deficit (CwHD), we measured center-of-pressure (COP) variability, mean velocity and entropy in bipedal quiet stance (feet together) with or without the concurrent cognitive task (reaction to visual stimulus) on hard or foam surface in 29 CwHD and a control group of 29 typically developing children (CON). The CwHD displayed an overall decreased postural performance as compared to the CON in the medial–lateral plane (p < 0.05). Standing on foam pad revealed slower simple reaction time in the CwHD (p < 0.05) while the results on hard surface were not different. The CwHD decreased (p < 0.05) the amount of attention invested in posture during dual task which accounted for the need of more cognitive resources to handle two tasks simultaneously than controls. It was unmistakable that the intergroup differences emerged when the tasks performed were relatively novel and untrained: feet together, foam pad, and reaction time. All these tasks, while being very easy for the CON, made the CwHD deteriorate postural or cognitive performance. These results unravel the difficulty in reaching the consecutive developmental stages in the CwHD and call for specific therapeutic modalities that might facilitate this development.