Moire patterns are interference patterns that appear when two similar patterns say two fine grids or two sets of closely spaced circles are moved in different ways. I stumbled into Moire patterns when testing my software sound synthesiser called DIN Is Noise. There is an instrument in DIN called Mondrian where balls bounce inside boxes and trigger notes when they hit the walls or the ceilings. A triggered note is visualised as a circle whose size increases as the note rises in volume (attacks) and then reduces as the note falls to silence (decays). In this video, a ball bounces really fast in a very tiny box. The notes triggered had long attack and short decay times. And by design of the instrument their frequencies are very close to each other too. The rising and falling circles interfere to produce Moire patterns [not so surprising] but then i realised the sounds were beating ...wow..thats interesting! But why? Then I realised when the frequencies of triggered notes are so close to each other they amplify and cancel each other producing beats!
Hope you enjoy the video and please upvote me if you can. I've been independently working on DIN Is Noise for the last 11 years and your support will help me continue my research and work on DIN.