Imagine a gathering at your home. A friend or relative excitedly wants to share a photo or video on your living room TV via Chromecast. Before you've managed to dig out your WiFi password, hand it over, and get the device connected, the magic of the moment is over. That soon will become a thing of the past, however, thanks to ultrasonic sound waves.
This is how it will work in theory, once it has been implemented. First, an owner must enable Chromecast to allow requests from nearby devices. Then, someone within the vicinity will send a request using any Chromecast-enabled app. Once Chromecast receives the request, it will send out a unique ultrasonic sound through the TV speakers. This sound is inaudible to human ears but is perfectly fine for mobile device microphones. This will complete the handshake and pairing will be established and fun can be started.
This was the new technology revealed by Google at I/O 2014. The original idea of employing ultrasonic sound for pairing and sending messages was already in the making, having been conceived and demonstrated by Google engineer Boris Smus last year. Google is definitely no stranger to the use of sound for such purposes. Last February, it acquired startup SlickLogin which employs a similar technology as a form of two-step authentication.
There is no exact timeline when this new feature will be made available, but Google says it will roll out improvements, which include customizing the Chromecast home screen, over the coming weeks. And before you start worrying, there is also an option to use a four-digit pin as an additional security measure, to ensure that your neighbor won't hijack your TV for nefarious and potentially embarrassing purposes.