An acoustic metamaterial comprising: a plurality of cells configured to detect and digitally process an incoming sound waveform in three dimensions, and to produce a corresponding response sound waveform as a function of a frequency and a phase of the incoming sound waveform , to produce a response sound waveform in three dimensions that, when combined with the incoming sound waveform , produces a modified sound waveform , wherein each of the cells comprises: at least one signal processor and at least one speaker ; a central hub containing said at least one signal processor ; and said at least one speaker ; a set of four beams, each comprising a solid material and further comprising a digital communications line; and a set of four microphones connected at corresponding ends of the set of four beams, opposite the central hub of each cell , wherein the microphones are configured to detect incoming sound waveforms , and the processor is configured to analyze features of the incoming sound waveform and to cause the at least one speaker to emit the response sound waveform that, when combined with the incoming sound waveform at a given corresponding cell, modifies at least part of the incoming sound waveform , wherein the cells are tetrahedral cells and a cell at an edge of the structural metamaterial is electrically connected with at least two other cells, and wherein a given interior cell inside of the edge is electrically connected with at least four other tetrahedral cells. a plurality of cells configured to detect and digitally process an incoming sound waveform in three dimensions, and to produce a corresponding response sound waveform as a function of a frequency and a phase of the incoming sound waveform , to produce a response sound waveform in three dimensions that, when combined with the incoming sound waveform , produces a modified sound waveform , wherein each of the cells comprises: at least one signal processor and at least one speaker ; a central hub containing said at least one signal processor ; and said at least one speaker ; a set of four beams, each comprising a solid material and further comprising a digital communications line; and a set of four microphones connected at corresponding ends of the set of four beams, opposite the central hub of each cell , wherein the microphones are configured to detect incoming sound waveforms , and the processor is configured to analyze features of the incoming sound waveform and to cause the at least one speaker to emit the response sound waveform that, when combined with the incoming sound waveform at a given corresponding cell, modifies at least part of the incoming sound waveform , wherein the cells are tetrahedral cells and a cell at an edge of the structural metamaterial is electrically connected with at least two other cells, and wherein a given interior cell inside of the edge is electrically connected with at least four other tetrahedral cells. at least one signal processor and at least one speaker ; a central hub containing said at least one signal processor ; and said at least one speaker ; a set of four beams, each comprising a solid material and further comprising a digital communications line; and a set of four microphones connected at corresponding ends of the set of four beams, opposite the central hub of each cell , wherein the microphones are configured to detect incoming sound waveforms , and the processor is configured to analyze features of the incoming sound waveform and to cause the at least one speaker to emit the response sound waveform that, when combined with the incoming sound waveform at a given corresponding cell, modifies at least part of the incoming sound waveform , wherein the cells are tetrahedral cells and a cell at an edge of the structural metamaterial is electrically connected with at least two other cells, and wherein a given interior cell inside of the edge is electrically connected with at least four other tetrahedral cells. <EOS>