Fans have flocked to a church in Germany to hear a chord change in a song which lasts for 639 years.
Soprano Johanna Vargas and composer Julian Lembke at the Saint Burchardi Church in the city of Halberstadt. Photo: AFP
It is the first chord change to As Slow As Possible in seven years.
The song by avant-garde composer, John Cage, is the world's longest and slowest piece of music.
The piece began 19 years ago with a pause lasting nearly 18 months. The change of chord took place on the specially built organ on which the composition is being performed.
Sand bags were attached to the organ, which coincides with what would have been Cage's 108th birthday, setting it to play G sharp and E for the next 2527 days.
"The sound from October 5 2013 until today, September 5, Cage's 108th birthday, is the longest uninterrupted sound," said Rainer Neugebauer of the John Cage Organ Project.
People queue to enter the church to hear the chord change. Photo: AFP
The Saint Burchardi Church in the city of Halberstadt started playing the song in 2001 and the last note change took place in 2013.
The score is made up of eight pages of music, to be played at the piano or organ - very slowly.
But the wait for the next scheduled chord change will be quick in comparison - with 5 February 2022 slated as the date.
The song will end in 2640.
Photo: AFP
Cage, who died in 1992 at the age of 79, wrote the piece in the 1980s.
The composer is arguably most famous for 4'33", which is simply made up of four minutes and 33 seconds of silence.
-BBC / Reuters