A spatio-temporal (ST) three dimensional (3D) polyphase-DFT cone filter bank is proposed for the selective filtering of 3D plane waves (PWs) in which a conventionally fully decimated temporal polyphase-DFT uniform-band structure is employed in the analysis and synthesis sections. Following temporal decimation in the analysis section, the 3D signal is filtered in each band with second-order uniform-bandwidth 3D IIR beam filters. The ST-domain input-output behavior of the proposed polyphase filter bank closely approximates that of a 3D cone filter, where the cone-shaped may correspond to either stop band or the pass band of the filter bank. Experimental results are presented that confirm the performance of the proposed 3D polyphase-DFT cone filter bank as a means of selectively filtering broad band 3D PWs on the basis of their direction of arrivals (DOAs).