“Is that how I sound?” exclaimed dancer Tiler Peck, reminding everyone around her at the premiere screening of the documentary Ballet 422 that ballerinas are usually seen and not heard. Peck was not even aware of the cameras because Jody Lee Lipes’ film was meant to be a promotional short; that he was taking sound was news. Lipes had so much rich footage, the decision to make a feature seemed the next big move. The result, an engrossing backstage glimpse into the making of a ballet from dancer/ choreographer Justin Peck’s initial conception through casting, lighting, costuming, and the vital give-and-take between choreographer and dancers up to the staging of the New York City Ballet’s 422nd work, “Paz de la Jolla.” Justin Peck (no relation to Tiler) is part of the NYC Ballet’s corps de ballet, and like Tiler, became part of the 90-dancer group at age 15. Among other revelations is that dancers double in other aspects of the ballet’s creation.