South Korea's giant walls of loudspeakers broadcast "news reports" boasting of their prosperity, aiming it at both North Korean border troops and villages near the border. They occasionally play music or radio dramas, though the main point is to demoralize the other side.
Spokesman Choi Hoi-Hyun told reporters the move was intended to "ease military tensions" ahead of Friday's summit,and also aims to set a new tone.
South Korean officials would not say if the loudspeakers would remain off after the summit.
The expectation though is that the summit will include more discussion of a peace treaty, formally ending the Korean War, which is still ongoing since 1950. If a peace deal happens, there would clearly be no need to broadcast such messages across the border any longer.