A Graphic Score, or graphic notation, is the representation of music using symbols or pictures outside those used in traditional music notation. It evolved as an artform in the 1950s, and can be used either in combination with or instead of traditional music notation. Composers quite often use graphic notation in experimental music, where standard musical notation doesn't tell the whole story. It is a particularly effective method for portraying texture to musicians rather than linear music, those who play traditionally melodic instruments that may not be used to providing texture in ensemble pieces can use graphic scores to interpret texture over melody.
It is also sometimes used in pieces where the composer wants to introduce an accidental element to the score, sometimes known as an aleatoric style. Or where they want to encourage improvisation and produce an undetermined effect on the music in performance. Alongside John Cage, one of the earliest pioneers of the technique was Earle Brown, who "sought to liberate performers from the constraints of notation and makes them active participants in the creation of the music." (Richard Taruskin).
The score shown above is from Trench Symphony and was used for the 'Reality' section of the piece. Charlie was trying to portray a sense of the battle, the space between, the horror and the tedium of No Man's Land. It was accompanied by a list of 'instructions' which gave the performers insight into each image on the score and the composer's intentions.
The choir's line was 'conducted' by the composer, a series of movements corresponding to sounds allowed the choir to improvise as one, adding texture and dissonant harmonies to the piece. During the performance the names of soldiers ring out from the choir, overlapping and at intervals, it was inspired by a body density map of the Somme, seen by Charlie on a research trip to Imperial War Museum London. One audience member remarked that in performance it sounded like "The souls of the dead calling out around the battlefield"