The correct answer to this open question is the following.
Arnold Schoenberg invented the twelve-tone technique or twelve-tone serialism to organize the atonal composition. In this system, each tone is given equal importance.
Arnold Schoenberg (1874-1951) was an Austrian composer, naturalized American that created the 12-tone system of composition. It provided a new musical structure compared with old tonality. Instead of just using one or two tunes, Arnold Schoenberg used 12 tones for compositions. In the system, no note would predominated nor had a hierarchy in the composition. The basic set of notes was known as the 12-tone row. Other composers followed his new system such as Alban Berg and Igor Stravinsky.