tcpsound utility will play sounds in response to network traffic permitting a user to literally listen to a network.
Specifically tcpsound forks a pseudo terminal in which to run tcpdump(8), parses that output, and plays a wide variety of user configuable sounds. Interpreting the output of tcpdump in a pty permits tcpsound to first ssh(1) to a remote host if desired.
To install tcpsound you will need tcpdump(8) on the machine on which you will be capturing packets.
On the local machine (where you will be playing the sounds of those packets) the libsdl sound library and unless you're using the OSX binary package libmba-0.9.1 or later is required.
Libsdl is fairly standard on Linux machines but you may need to install development packages (specifially SDL-devel and SDL_mixer-devel for my RH 7.3 machine).