Working with Fable 5, a MacBook, and a Pixel phone, I built an acoustic transport library that is several orders of magnitude faster than existing SoTA open source options like ggwave, quiet, minimodem, or Chirp.

Paper: https://cyrinx.org/cyrinx-acoustic-link.pdf

Apache 2.0 source: https://github.com/dweekly/cyrinx

Really cool. I still miss the modem days... started at 2400 baud.