Google wants to make the experience of using Chromecast more social. Announcing the new feature during yesterdays I/O keynote, Chromecast Product Manager Rishi Chandra said, We’re using a variety of different technologies, which allows us to authenticate users in the same room as Chromecast. But considering how cool one of those technologies is, its surprising that Chandra didnt offer more details. GigaOm says Googles using ultrasonic audio cues to help make the connection between smartphones, tablets, and your TV.