Sara Myers and her voices are the show's earliest fully-disclosed supernatural mechanic. In S1 she heard voices that compelled her to harm others, including the attack on Ethan and the killing of her brother Nathan. Father Khatri treated the voices as a possible communication channel. He died protecting her. The voices were quiet through S2-S3, until S4E4 when Sophia whispered something inaudibly in her ear and they returned.
Julie spends much of the episode with Sara, painting her house. Reading this charitably: Julie may be the only person whose presence creates a quiet space where MIY's voice loses purchase. Reading it darkly: the calm is preparation for a larger role.
Voices being MIY's is confirmed. Open: what Khatri got right vs wrong about them being a channel rather than just control.