For that reason, he used a knife with which he marked the divisions of tones in the strings of his violin until obtaining 16 different tones -microtonos. Microtones are units of musical scale whose magnitude is less than the semitone, for example: the sound between a yes and a b flat.
When it was found that a tone can be divided into more than 16 microtones -Carrillo recorded up to 128 divisions of tone-, new sounds and scales were discovered in the music. Several scholars and music theorists, as well as instrument manufacturers, undertook reforms in the manufacture of pianos, harps, flutes and guitars to reproduce these sixteenths of tone.
Carrillo’s discovery broke with the classical classification of the 12 tones – hence the name of Sound 13 -, revolutionized modern music and opened a huge range of creative possibilities.
Sound 13 is not exclusive to contemporary abstract works, its tone was already used in traditional music; as in the Arab songs and the melodies of India; similar to an out of tune piano.
Because new sets of sounds were created, it was imperative to make a new notation system.
When notating music, Carrillo used a staff. However, instead of using lines to signify different notes, he used the lines to distinguish between octaves so that each line on the staff represents a different octave. For example, if 0 on the second line of the staff denoted what conventional music terms middle C, 0 on the third line would refer to C an octave higher, and 0 on the first line would refer to C an octave lower.
Carrillo used many intervals, although mainly in multiples of 4 such as 16, 32, and 64 so that between each of the whole tones, 16, 32, or 64 additional notes were created. Carrillo called these intervals 16hs of a tone, 32nds of a tone, and 64ths of a tone, respectively. As a result, C would be labeled 0, D flat would be labeled 8, D would be labeled 16, E flat would be labeled 24, E would be labeled 32, etc., for 16ths of a tone.