Comment by WestCoastJustin

There have been several threads on HN about ultrasonic networking in recent months. One was a simple chat client, called Quietnet [1]. The other was malware called BadBIOS, which has the ability to communicate over hi-def audio [2].

[1] https://news.ycombinator.com/item?id=7024615

[2] https://news.ycombinator.com/item?id=6654663