The Solaris `snoop` command for capturing network packets has supported a -a option for at least 20 years which listens to packets on /dev/audio and comes with a warning that it "may be noisy". It used to be fun to run on a Sparcstation!
(Hauling out this device would've been even cooler, had we dimmed the cube farm overhead lights, and worn 37337 hax0r sunglasses.)