The project began when the Kronos Quartet asked Reich to write a piece that utilized pre-recorded voice parts to go along with the music . Reich recalled an idea he had in 1973 of drawing out the end of the speaker 's words . In January 2010 , Reich decided to use voice recordings related to the September 11 attacks , specifically recordings from the North American Aerospace Defense Command ( NORAD ) and the New York City Fire Department ( FDNY ) , as well as parts of interviews with friends and neighbors of Reich that lived in Manhattan at the time of the attacks . Reich 's son , daughter-in law , and granddaughter were staying in Reich 's apartment , four blocks from the World Trade Center , at the time of the attacks . '' WTC 9/11 '' is the third " major commission " for Reich to write for the Kronos Quartet
September 11 attacks
September 11 attacks
WTC 9/11