I wonder how practical this would be in reality, the frequency response of a typical built-in PC speaker and microphone should be severely limited. And in addit

I wonder how practical this would be in reality, the frequency response of a typical built-in PC speaker and microphone should be severely limited. And in addition to this there would probably also be quite a big problem with background noise, which would get worse as the distance between the machines gets larger. I guess you could use error correction and handshakes to retransmit corrupted data, but that would limit the transmission speed even further.