Oh my gosh. Do you have a link of where she said this?
Ugh I can't find the link anywhere but I think it was an interview from the Stronger era? It was when she first talked about it, she said the only reason she knew when to start singing in that performance was because she felt the vibration in her butt
She also said she got shocked because the mic they ran up and gave her was corded, and it was close to the pyro or something
At the beginning of her part, neither her in ears or her mic were on. The mix was all off, and then near the end, Jason's mic randomly went off so she's singing the harmony by herself