In complex communicative scene, listeners can selectively focus their attention on the position of the target speaker based on their communicative intentions, suppress sound input from the same or different spatial positions and effectively process the information of the target sound. However, it is currently unclear how different types of interfering sounds affect the allocation of auditory attention resources when listener selectively processes the target sound, and how attention regulates cortical responses from top to bottom to locate and perceive the target sound. This article mainly focuses on how the spatial position of speech and the number of speakers in the masking speech affect auditory attention. The experimental results indicate that the interaction between the spatial position of speech and the number of masking speech affects the efficiency of processing target speech. The separation of masking and the spatial position of the target speech can promote the perception of the target speech, manifested as an enhancement of cortical response. However, the advantage of spatial position separation in promoting target perception is also affected by the number of masking speech. In addition, this paper also found that the brain has the advantage of spatial location selectivity and attention resource allocation in processing target speech input from different directions.