The goal of this thesis is to study the timbrical relations between different instruments throughout the 20th and 21st century. Attending the so called fusion or illusion-technique and analyzing some musical parameters and psychoacoustics, we will realize how relevant composers focused their work on mixing timbers in order to articulate their own musical language.

The motivation of our research will try to understand what a priori seems hidden for the hearing, it means therefore that we will isolate and study the elements that we cannot separate while listening the analyzed pieces. This will provide us the tools in order to understand how each compositional thought is articulated and, besides, why the selected pieces have a special place in the history of the music from 1950.

In order to understand how instrumentation, that is, the relation of timbres between different instruments plays a fundamental role in the musical language of some composers, we have decided to choose the following pieces due to their relevance not only in each composer’s Oeuvre, but also in the history of the instrumentation of chamber music. Besides, the proximity in time of the first three works can represent the variety and diversity of esthetical positions that were lived in the late sixties:

G. Scelsi´s Okanagon (1968), G. Ligeti´s Kammerkonzert für 13 Instrumentalisten (1969-1970), temA (1968) by H. Lachenmann constitute a group of pieces that not only were composed in the same period, but they are crucial to understand the change of paradigm in the musical language of the second half of the twentieth century.

Quaderno di Strada (2003) by S. Sciarrino, Ceux à Qui (2015) by R. Lazkano and Arquitecturas del límite (2005-2012) by J. Mª Sánchez-Verdú represent on the other hand a new generation of composers -in relation with the mentioned ones- that do not belong anymore to the period in which the first experiments were done, but to a consolidated generation that inherits the challenges of the end of the 20th century and beginning of the 21st. That is why we have considered confronting the idea of the instrumentation in the sixties with the current time (from 2003, that is, at least 27 years between Partiels and Quaderno di Strada, and at most 47 between temA and Ceux à Qui)

All these pieces, despite of their esthetical differences, share something in common that led us to their choice: the balance and the unity of the instruments in order to create a superior entity is crucial to understand the piece and, as consequence of that, the composer’s musical thought.

Before we analyze the mentioned pieces, we will start the first chapter describing what we understand as “meta-instrument”: its diverse visions and acceptances not only in the musical field, but also in other artistic expressions with all their contradictions, will be our point of departure.

In the second chapter we will focus on some musical parameters that will expand our theoretical definition of “meta-instrument” and will help our analysis with precise tools.

The third and central chapter consist of an analysis of the mentioned pieces, always orientated to the idea of the “meta-instrument” and how it plays different roles according to the esthetical position in each composer.

The fourth chapter reflects about the reception of the “meta-instrument” concerning psychoacoustics and the concepts of brevity, quickness and dynamics.

The last chapter will try to show our conclusions and will bring into discussion the role of the “meta-instrument” in the current and future generations of composers.