Mentioned in the article, but forced rhubarb grows so fast you can hear it. This soundcloud file suggests hearing it in a darkened vault by candlelight would be extraordinary experience!
I don't quite understand: constantly, for days? It seems there would be a finite # of buds to burst, and especially at the frequency (4-6 hz?) and relatively finite size of the dark greenhouse...I'm really surprised this is a phenomenon for more than hours. There must be a TON of buds?