Sport is never silent. The crack of the bat, the roar of the crowd, the "oof!" of a tennis pro connecting with the ball help us feel present -- even if, like the millions of us watching on TV, we're not. Yet even when we're at the event, we don't hear it all. In stadium sports, the cries of fans drown out the sounds on the field. At rowing events, the creak of oars and the gurgle of water, are muffled by distance or drowned by the noise of camera-copters. Viewers of this year's televised Olympics, though, will hear far more of it. At many events they'll be immersed in sounds that bring home the reality of sport as never before -- sounds never heard by live spectators and sometimes not even by participants.