Without criticizing their singing ability -- because who cares, really? they're elated and want to sing, etc. -- it highlights what I suspect are some issues with timing and the speed of sound that seem to be an issue in large stadiums without microphones.
Have the crowds been especially rowdy at these games? Delaying the 200m and booing the gymnastics judges -- at last, a little of that anti-Americanism that we were told to expect!
Compared to swimming, the track competitors seem to be a little more faith-based and the qualifying rounds seem to stretch on forever. Maybe there are more contestants?