In this article we explore the influence of a microphone array’s inherent noise on the efficiency of the spatial processing of wideband speech signals; on the accuracy of determining the directions from which acoustic signals arrive (if a microphone array receives two broadband acoustic signals at the same time); on the degree of interfering signal suppression; on the subjective assessment of the interfering signal which is not completely suppressed. The inherent noise of the array introduces an error in determining the signal source direction. The authors have obtained mathematical dependences which allow to find the ultimate signal/noise ratio, providing the interfering signal suppression which satisfies a predetermined expert opinion value.