This is the first chord change to As Slow As Possible in seven years.
The song by avant-garde composer John Cage is the longest and slowest piece of music in the world.
The play began 19 years ago with a hiatus of almost 18 months. The chord change took place on the specially constructed organ on which the composition is performed.
The Saint Burchardi Church in the town of Halberstadt started playing the song in 2001 and the last note change was in 2013.
The score is made up of eight pages of music, to be played on the piano or the organ – very slowly.
But the wait for the next planned change of agreement will be quick in comparison – with February 5, 2022 as the date.
The song will end in 2640.
Cage, who died in 1992 at the age of 79, wrote the play in the 1980s.
The composer is arguably the most famous for 4’33 ″, which is simply four minutes and 33 seconds of silence.