Yes kinda, I would say network activity rather then traffic. Audio signal is going to be in scale of 48Khz while measuring ethernet signal at scale of 100Mhz. At that rate it wouldn't even get more then 1 sample from a full size packet. So really it's polling 48Khz whether or not there was activity during that period. The gimmick is that it uses some analog components. Fully digital you could craft a meaningful audio signal that represents traffic.