Richard Reed Parry's Duet For Heart And Breath Treble Clef version for Viola (or other instrument of suitable range) and Piano (or other polyphonic instrument).
The performers wear stethoscopes positioned over their hearts so that each can follow his or her own heart rate. Two eighth notes (quavers) correspond to the two sounds of a normal heartbeat, and performers should match as closely as possible the staccato and irregular rhythm they hear. When instructed to ‘play to breath’, the natural cycle of one inhalation and one exhalation, or vice versa, will determine the length of the bar (two quarter notes/crotchets) without any attempt to make it metronomic.
'This piece is based around the idea of using the widely varying internal rhythms of the performers’ bodies as performance parameters. There is no actual tempo or meter built into the piece. The breathing rates of the players are used in alternation with the individual performers’ heart rates to determine the pace at which all of the musical material is played. This requires that the performers generally play quietly and delicately, with little or no vibrato, so as to be able to hear their heartbeats adequately. This, in combination with thenatural variance between the different heart rates, results in a kind of delicate musical “pointillism”: starts and stops which are somewhat staggered, parts which repeatedly line up and fall out of synch with each other, different individuals’ pulses rising and falling. The piece is never performed exactly the same way twice.' - Richard Reed Parry.