sixty-five minutes long - two periods of thirty minutes each, with, a five minutes silence between them
each performer finds one sound, preferably with pitch
this sound is played for one duration, between one and fifteen minutes, in each thirty minutes period, making sure, in the first period, not to cross over period into the silence
the duration of the sound may change from one period to the next
the sound may be sustained for the whole length of the duration chosen - or if it is impossible to sustain the sound for the duration, long sounds may be repeated at regular intervals
the loudness of the sound is in inverse proportion to its duration - i.e., the longer the duration, the softer the sound the one minutes duration should be a comfortable mp; a fifteen minutes duration will be nearly inaudible