A sound icon is a grand piano standing on its side. It is primarily played by bowing the strings. It was the invention of Romanian-French composer HoraÃÂiu RÃÂdulescu, who featured the instrument in several of his pieces.
HoraÃÂiu RÃÂdulescu first conceived of the sound icon in 1965. It consists of a lidless grand piano that has been placed on its side, so that it resembles a harp. Typically, nylon cords are rubbed with rosin and woven behind the piano strings. When the cord is bowed against the string, it creates a unique timbre which has been described as "sounds of an infinite resonance that have no equivalent among other instruments".
RÃÂdulescu called his invention a sound icon, because he conceived it while living in Romania where "religion was onlyâ¦possible through music". To RÃÂdulescu, the striking image of the grand piano on its side presented the instrument "in a new light; it now resembles a religious object â a Byzantine icon". The name also has a punning connotation because its acronym is "si", the French and Italian syllable for "B".
The sound icon is played in several ways. The primary technique is to bow the strings, a tradition which dates back to instruments like the bowed clavier and the hurdy gurdy. Unlike those instruments, which rely on rosined wheels to stimulate the string, the sound icon is bowed by weaving material between the strings. RÃÂdulescu is reported to have used a variety of materials to both bow and pluck the piano strings, including fishing line as well as gold coins.
The seminal technique for bowing the sound icon is to use a single horsehair as thin as 0.1 mm in diameter. RÃÂdulescu was preoccupied with "reversing the proportion of the bows and strings" usually found in a violin. He wound the horsehair in a "V" shape around the string. Bowing the horsehair makes the piano string vibrate and creates a sympathetic resonance in the other strings. The location of the bow on the string also creates a dramatic difference in the resulting sound. In works with multiple sound icons, RÃÂdulescu would weave "spider webs of nylon threads of different thickness in between the pianos".
In each piece, RÃÂdulescu would work out a very precise tuning for the sound icon to control the timbre of its sympathetic resonance. He called this tuning a "spectral scordatura". RÃÂdulescu compared the droning nature of the sound icon to the Indian tanpura.
HoraÃÂiu RÃÂdulescu featured sound icon in the following works:
Because of the difficulty of vertically orienting a grand piano, composers often simply write for "bowed piano", using the technique that RÃÂdulescu pioneered. Composers like John Oliver, Kirsten Broberg, and Stephen Scott have all written for bowed piano. Scott even formed the Bowed Piano Ensemble. Bands like Wilco and the Nitty Gritty Dirt Band have also used bowed piano.
In 2015, the sound icon was assigned as part of the instrumentation at Iron Composer.