At first I thought the file sharing itself was over sound, but the sound is just to negotiate details of the WebRTC session which is then actually used to transmit the data. Neat and handy.
I was thinking they had made something similar to the Fldigi suite, software kind of common in the ham radio universe. You can use it to encode arbitrary binary data into a lot of different modulations which exist in the audible range. Send files between computers without any IP networking at all.
What throughput can you get with audible sound?
Thinking of dialup networking, I guess somewhere around 56 kilobits per second is certainly feasible? hehe :)
I was thinking the same. Minimodem[1] turns devices into FSK communication devices. Analogous to transferring information via dial-up.