Microsoft awarded patent for Chromecast's technique of confirming proximity using audio signals

Google’s Chromecast has a simple technique to allow guests to stream to an open Chromcast device by confirming their proximity using audio signals, so called “audio pairing”. This involves the Chromecast enabled TV broadcasting inaudible sounds which are picked up by the Google Home app on a phone, and which then confirms to both parties that they are in the same room, preventing someone who is far away or somewhere else in the home from suddenly cutting into your viewing.

Now Microsoft has been awarded a patent for this technology.

The United States Patent 9,756,438, filed for on the 24th June 2014 and only granted on the 5th September 2017, for “Proximity discovery using audio signals,” reads:

Various technologies pertaining to computing data that is indicative of a location of a client computing device are described herein. A client computing device is configured to capture an audio signal, the audio signature being indicative of acoustics of surroundings of the client computing device. A signature is generated based upon a high frequency portion of the captured audio signal, and the signature is compared with other signatures. The other signatures are generated based upon high frequency portions of audio signals captured by other computing devices. A determination regarding the client computing device being co-located with a second client computing device is made based upon the comparison of the signature with the other signatures.

Unlike the patent applications we often write about, this is an actual granted patent, and while we are not aware of any Microsoft device using it, we do wonder if Google will now have to change the way they pair their devices.

The full patent can be read here.