It is well known that bilateral superior temporal gyrus (STG) specialize in speech perception. However, there is no study to explicitly represent the interaction between the bilateral STG depending on hearing condition (i.e. binaural or monaural hearing) based on neuroimaging findings. To this end, speech sentences containing numerical sound(s) were provided in binaural, monaural left and monaural right hearing condition. Participants were asked to correctly identify the presented numerical sound and speech hearing performance was calculated based on the number of correctly identified sounds. From the results, neuronal activations of the right STG were shown significantly different levels of neuronal activations across the three hearing conditions. In addition, the neuronal networks that are functionally connected with this right STG and associated with the speech hearing were iteratively identified in the bilateral STG. The reported findings support the importance of the right STG toward the enhancement of the speech hearing performance.