10 years ago I made an "encrypted voice channel" by chaining the following 3 commands together (I dont remember exactly how it looked, this is just a sketch):

    arecord - | openssl aes-128-cbc -pass:'secretstring' - | nc <dest ip> <dest port>

on the receiving end

    nc -l <dest port> | openssl aes-128-cbc -pass:'secretstring' | aplay -

I don't remember exactly which audio device I used back then. It worked okay-ish, but there was definitely lag from somewhere. Just kind of neat that you can build something so useful without a bloated app, just chaining a few commands together.