Although commonplace today , the effect bewitched audiences in the era before widespread recorded soundâ '' after the initial 1918 run-through , Holst 's daughter , Imogen ( in addition to watching the charwomen dancing in the aisles during `` Jupiter '' ) remarked that the ending was `` unforgettable , with its hidden chorus of women 's voices growing fainter and fainter ... until the imagination knew no difference between sound and silence '' . Although commonplace today , the effect bewitched audiences in the era before widespread recorded soundâ '' after the initial 1918 run-through , Holst 's daughter Imogen ( in addition to watching the charwomen dancing in the aisles during `` Jupiter '' ) remarked that the ending was `` unforgettable , with its hidden chorus of women 's voices growing fainter and fainter ... until the imagination knew no difference between sound and silence '' .