This PhD thesis consists of eight middle-size compositions and a written commentary. Each of the pieces explores a different pitch system. In Chapter 1, the aesthetic behind these pieces is discussed. This is based on the transformation of a single unifying sonority; every note has a function both in the moment and on a large scale. This implies a hierarchy that is established through techniques derived from Schenker and Lerdahl’s analytical methods, which are also explained. The following chapters apply these methodologies in the analysis of the eight pieces, unveiling a good deal of techniques and compositional issues derived from those presumptions. Momentum for 4 percussionists deploys rhythmic gestures, patterns, and regular pulsations. The piece has a ‘moment form’, where the materials are in constant transformation and the concept of balance emerges as a compositional issue. Knots in Time for ensemble makes use of a functional harmony constructed by analogy with the tonal system. In Looking forward/backward for ensemble modal and serial techniques merge with harmonic fields and pitch-class set techniques. The ‘solution’ to this puzzle is found through an extension of Schenker’s reduction techniques so that each of these conflicting systems belongs to a deeper or a more superficial level of the music. Across 1000 Oceans for String Trio is an instance of geometry applied to music since it uses quasi-symmetric and symmetric chords as a means to create tension and relaxation in the phrasing. Hasta dentro de un solo, Nunca más solos for scordatura violin is a synthesis of the previous compositional techniques. Fractal for 2 pianos is based on the fractal geometry. Interlude for piano and instrument uses registration as a structural element. In both cases, the geometric organization is enhanced to create an ‘organic’ form. ‘Organicism’ and ‘fractality’ are also compared, hypothesizing that Romantic writers had in mind a fractal model when discussing their ideas. Finally, Genesis Songs represents a hypertext in which several musical traditions coexist in a collage typical of the postmodern aesthetic, which is also discussed. These disparate materials challenge the classical conception of autonomous work or opus perfectum et absolutum.