 A few composers have written symphonies for unaccompanied chorus , in which the choir performs both vocal and instrumental functions . Granville Bantock composed three such works — Atalanta in Calydon ( 1911 ) , Vanity of Vanities ( 1913 ) and A Pageant of Human Life ( 1913 ) . His Atalanta , called by musicologist Herbert Antcliffe " the most important [ work of the three ] alike in technical experiment and in inspiration " , was written for a choir of at least 200 , the composer specifying " ' not less than 10 voices for each part , ' " a work with 20 separate vocal parts . Using these forces , Bantock formed groups " of different weights and colors to get something of the varied play of tints and perspective [ of an orchestra ] " . In addition , the choir is generally divided into three sections , approximating the timbres of woodwinds , brass and strings . Within these divisions , Antcliffe writes , 
