for light, you are mostly correct. LED strips over a sheet with a diffuser produces a more useful light. But, as light is in the Thz range, doing any meaningfu

for light, you are mostly correct. LED strips over a sheet with a diffuser produces a more useful light. But, as light is in the Thz range, doing any meaningful beamforming is exceedingly difficult. Because speakers are well within the range of controllability, its perfectly possible to alter the phase to steer the audio output. this is possible because changing the phase moves the peaks and troughs of the waves to "move" the sound to where its wanted.