Each player works their way through the piece independently, but listening carefully to the others so as to be aware of the effect that what they play has on the overall sound.
Each bar contains a group of notes. The performers should proceed from bar to bar, playing the notes in each bar in any register, any order, any number of times, sometimes oscillating between the given notes, sometimes holding a pedal, sometimes playing "singingly" - either single notes or motifs drawn from the available notes in the bar being played. Each bar should be played until the player feels they have explored it sufficiently, then move on. The players should not coordinate movement from bar to bar, so that the harmonies blur . Each bar should probably be played for at least 45 seconds - a minute.
When everyone has reached the final bar, continue for some time (at least a minute) until everyone is playing a unison E (i.e. the exact notated pitch, unless this pitch is unplayable on the instrument, in which case drop out), then finish at an agreed signal.