it perfects the pitch of your voice or something, idk.
from what i understand it's just used to make you sound better.
hayley only used it once, during the MTV Live performance, but it wasn't by choice. the people that broadcast the show made her do it.
i don't get how you use that live, but whatever.
anyways, someone posted a secret saying that she uses it during ALL the shows, and hayley commented to defend herself. everybody got all worked up that she actually read the secrets sometimes, and so the community was deleted.
apparently it's back up now, but they're making new rules so that nobody can post secrets about their families anymore. i guess we'll see how that works out.