 After completing Licht , Stockhausen embarked on a new cycle of compositions , based on the hours of the day , entitled Klang ( " Sound " ) . Twenty @-@ one of these pieces were completed before the composer 's death ( Stockhausen @-@ Verlag 2010 , 49 – 50 ) . The first four works from this cycle are First Hour : Himmelfahrt ( Ascension ) , for organ or synthesizer , soprano and tenor ( 2004 – 2005 ) ; Second Hour : Freude ( Joy ) for two harps ( 2005 ) ; Third Hour : Natürliche Dauern ( Natural Durations ) for piano ( 2005 – 2006 ) ; and Fourth Hour : Himmels @-@ Tür ( Heaven 's Door ) for a percussionist and a little girl ( 2005 ) ( Stockhausen @-@ Verlag 2010 , 49 ) . The Fifth Hour , Harmonien ( Harmonies ) , is a solo in three versions for flute , bass clarinet , and trumpet ( 2006 ) ( Stockhausen @-@ Verlag 2010 , 49 ) . The Sixth through Twelfth hours are chamber @-@ music works based on the material from the Fifth Hour ( Stockhausen @-@ Verlag 2010 , 49 ) . The Thirteenth Hour , Cosmic Pulses , is an electronic work made by superimposing 24 layers of sound , each having its own spatial motion , among eight loudspeakers placed around the concert hall ( Stockhausen 2007a ) . Hours 14 through 21 are solo pieces for bass voice , baritone voice , basset @-@ horn , horn , tenor voice , soprano voice , soprano saxophone , and flute , respectively , each with electronic accompaniment of a different set of three layers from Cosmic Pulses ( Stockhausen @-@ Verlag 2010 , 50 ) . The twenty @-@ one completed pieces were first performed together as a cycle at the Festival MusikTriennale Köln on 8 – 9 May 2010 , in 176 individual concerts ( Gimpel 2010 ) . 
