This is Barbie Parker giving an expressive performance in front of a crowd of thousands of cheering fans at Lollapalooza. If her name doesn’t ring a bell in your mental dictionary of rock stars, that’s because she’s never been a headliner–she’s a sign language interpreter who performs alongside hugely popular musical acts like Jack White and Green Day. Parker’s company, LotuSIGN, has helped bring sign language interpreters to more musical performances, and the demand for her services continues to grow. “Music is such a large part of who I am,” she said. “I want to be able to open up that experience.” Parker’s performances include air drumming, lip syncing lyrics, dancing, and jamming on an air guitar to communicate each concert to attendees who are deaf or hard of hearing. Check out a couple videos of Parker in action, after the jump!