A sound installation by Dohi Moon and Bjoern Erlach
Pulb is an installation in which a piano sound board is played by a machine dropping water at the strings to excite them. The strings respond with very soft vibrations to the impact of the drops. The vibrations of the strings are picked up with piezoelectric discs and are amplified by speakers. The resulting sounds exhibit very different characteristics from the sound of plugged piano strings or the sounds produced by the strings struck by a hammer. By adjusting the placement of the pickups different sounds ranging from loud percussive hits to very soft harp-like sounds. We searched interesting constellations of the pickups while having the machine drop water in different patterns. Much of the instrument's charm is due to the element of chance and the non uniformity between the sounds produced by the individual strings. The path the water takes through the air onto the pianoboard varies slightly from drop to drop. Sometimes the drops split and hit the strings in more than one position. Instead of trying to achieve the precision of a steril medical device we inserted bend needles into the water outlets to amplify the organic and slightly non deterministic behaviour. The organization of the drops is varied between random drops resembling rain falling on the board and repetitive patterns. If order is slowly introduced, patterns start to appear, at first seemingly accidentaly until recognizable repetitions of material occur.
Technical DetailsFour electrical valves trigger the water drops. Small flexible plastic hoses are connected to each of the valves. The water outlets at the end of the hoses are attached to motorized faders which can place the outlets in different positions above the board to aim at different strings. An Arduino board was used to control the faders and valves from a computer. The positioning of the faders and the triggering of the water drops is controlled by routines written in the SuperCollider language. Piezoelectric pickups are attached to the strings to amplify the vibrations.
On popular demand, here is Pulb playing a familar melody. Practice makes perfect. Jingle Bells?