If you've been watching the 2020 Masters live streaming -- the one without commentators -- then you no doubt have heard a constant humming as the players take on Augusta National.
Given how perfect things are at Augusta National, it might seem strange that this noise isn't going away. However, the noise isn't going away for a good reason.
The hum you're hearing is either that of the Sub Air system at Augusta National or drones.
Underneath every green at Augusta National Golf Club is what's called a Sub-Air system. It's effectively a vacuum underneath the green that allows the club to control the moisture under each putting surface. When it rains, as it did on Thursday morning to cause a three-hour suspension of play, the club can turn on the Sub-Air system to more quickly pull water out of the green and drain it away. This way, the greens get firmer and back to normal speeds sooner.
In addition to removing moisture from the greens, the Sub Air system can be used to blow cool air back into the greens to help keep them cool when it's particularly hot outside. That's obviously not a threat during the November Masters, but it's helpful in the summer months when the club is closed to play.
There are also drones flying around Augusta National this year. With no fans, CBS and the club are trying some new camera angles they couldn't otherwise use. Drones flying in the air make a more high-pitched sound because it isn't muffled underground.