Sonic Patterns

This video is quite fascinating. It shows how a different audio frequencies can create intricate patterns - in this case, from rice on a flat surface. It would seem to me that this would be affected by the arrangement of speakers below the panel, and the waveform being used to generate the sound. I wish the video had shown the experiment below and above the human range of hearing, because that would be a nice way to show that even non-audible 'sound' (vibrations) can affect us physiologically. In any case, it is still an amazing demonstration of interference patterns.