The piece "Organ 2 / ASLSP (As slow as possible)" is based on a work by the American composer John Cage.
The work was started in 2001 and the last time chords were changed was in 2013.
Visitors flocked to the church in Halberstadt in eastern Germany where the organ stands, writes Deutsche Welle.
Last time, 1,500 people came to see the chord change, but due to coronary restrictions, significantly fewer were allowed to watch the event this year.
The next chord change will take place in 2022
Until now, five organ pipes have played the same tone.
Two new organ pipes were started at 3 pm, which changed the chord.
The next chord change is scheduled for February 5, 2022, according to Syddeutsche Zeitung.
John Cage was a composer and sound artist who became known for his avant-garde works. Among other things, "4.33", a piece completely without tones. He died in 1992.