Sonido 13 is a theory of
microtonal music created by the
Mexican composer
Julián Carrillo around 1900 and described by
Nicolas Slonimsky as "the field of sounds smaller than the twelve
semitones of the
tempered scale." Carrillo developed this theory in 1895 while he was experimenting with his
violin. As he placed his finger over a violin string, he noticed that he could produce different sounds than the ones defined by musical convention. This way, he realized that the string could be divided into an infinite number of
pitches, creating many more possibilities for
music composition. Though he became internationally recognized for his system of
notation, it was never widely applied. His first composition in demonstration of his theories was
Preludio a Colón (1922).