mumblelink is a mod that adds support for positional audio functionality offered by TeamSpeak 3 or Mumble. In other words, depending on the player’s position within a Minecraft server, we may or may not be able to listen to them.
If we’re close we can talk, but if we’re far away we just won’t hear each other. It also allows for a much more realistic sound feel than the default. In the same way, if the player is on our right, we will hear him on the right, and if he approaches us, the sound level he emits will increase.