Cooper operated all five dummies and the projection of six voices. The extra voice was his, as he also had a role in the performance. In this scene, he multitasked by one of the dummies "cut the customer's hair" with his hands while using his feet to operate the other dummies.
Cooper coordinated all five dummies and the projection of six voices. He also had a role in the performance, which is why there was an additional voice. In this scene, he juggled multiple tasks by having one dummy perform a haircut with his hands while using his feet to control the other dummies.