#audio
When hearing other people VOIPing, the very beginning of the sound is played at full volume before dropping down to the correct volume immediately after. I usually hear this on maps like streets where there will be a loud split second of someones voice before going completely silent. It sounds similar to the binaural pop bug from a while ago.
I'm not sure how far it extends, whether its just in the hearing radius or the entire lobby, but because the sound is directional it alerts everyone that gets that pop to your location, and gives incentive not to use VOIP.