@vampirdaddy @swan_tower It's the same with the #recorder. Two is terrible, unless the players are really very good and can match pitch perfectly. But three or more are usually fine if the players are just moderately competent. In this case, the large number create so many constantly changing interferences that it becomes very pleasing. Having read a bit about the #matryomin (single-antenna #theremin inside a matryoshka doll, a commercial product), this choir may actually play some characteristic #formants in addition to the base pitches to simulate human voices.