The same technique was used in the first TV remotes[0]. It drove people with good hearing nuts, had interference issues with natural phenomena, and had fundamental bandwidth limitations.
Otherwise, it is a cleaver hack around the lacking device-to-device wireless support.
This looks similar to what http://chirp.io/ is doing, only more open. It's great to see interesting advancements like this, especially using web technologies.
Cool! I'm wondering how this could be used (or interfere) with a Parallax Ultrasonic Ping sensor for Arduino and other microprocessors. Maybe attaching the Ping sensor to a RasPi's GPIO (general purpose in/out) pins will allow for ultrasonic RasBMC remote?
Doubtful, any purpose built ultrasonic sensor will likely be running at much higher frequencies than you can play with via a standard audio chain. The Ping for example runs at 40khz but the most you'll get out of a standard issue audio chain is ~20-24khz, depending on the corner frequency of the analog filters on the input / output and driver / mic response.
That is interesting...assuming you can address individual devices and get some concept of relative position you can likely create some pretty interesting psychoacoustical effects with that many point sources. Probably highly dependent on being able to control relative latency though.
The same concept is currently being used by the Hex3 JAJA stylus to communicate pressure information - it is really quite elegant. http://www.hex3.co/products/jaja
Otherwise, it is a cleaver hack around the lacking device-to-device wireless support.
[0] http://en.wikipedia.org/wiki/Remote_control#Television_remot...