So, I've been wondering: how would time dilation affect communications? For the sake of visualisation, imagine the Flash is running at 99% the speed of light in a circle around a fixed position. There's a building in this position, and inside this building are his friends. Due to time dilation, they should be experiencing time at different rates. Assuming the usual problems(wind muffling comms, drag etc.), are a non-issue, and that he is talking to his friends through conventional radio communications, would others perceive him to be talking much slower than normal, if, from his perspective, he was talking at a normal rate? If so, at what rate would he have to talk to be able to communicate with them? If you'd prefer, you can swap the Flash for a spaceship and the building for an asteroid; like I said, it's just to help with visualisation.