For a time there was an interesting and somewhat absurd situation: it was avant-garde, highly complex, radical-sounding music that became the cultural mainstream. Young composers at conservatories in Europe and America were then taught to write only "modern".

https://www.youtube.com/watch?v=h6v3ImiqXro - Youtube to mp3 converter

The "second" avant-garde took up the ideas of the "first" avant-garde, but raised them to a whole new level. Tone sequences now consisted not only of 12 tones with non-repeated pitch, but also of different lengths and other characteristics. Composition became extremely rational. Each note had its logically defined place - its pitch, its length, the instrument on which it was played, the degree of emphasis - everything was mathematically calculated. This is a movement called serialism. The matter of such compositions sounds dry and explosive, a collection of hard musical points.

https://www.youtube.com/watch?v=F_9eg7T6s6o - Youtube to mp3 convert

The second area explored by avant-gardists is controlled chaos, specifically purposeful improvisation.

They write compositions in which musicians are given the freedom to create sounds that are not fixed once and for all in the notes, but are movable within certain "rules of the game." These sounds can even be completely arbitrary; or they can be extra-musical, like reading aloud or the static of a radio. Another important trend in the post-war avant-garde is the combination of conventional instruments with electronic sounds and the synthesis of purely electronic sounds that have no equivalent in nature.

Finally, one of the most spectacular discoveries of the avant-garde is sonorica.

A great movement in which many different techniques are used, linked by a particular attitude towards sound. In the past, composers thought in terms of notes - dots - which they strung together in a line, creating a melody - as if an artist were drawing with a sharpened pencil. Now imagine an artist putting the pencil aside and picking up a roller, a sponge, a stamp, or a mop: he gets dots, dots, dots. It is the same with sonorous music. It thinks in noise zones, complexes, sounds, moving volumes of sound. It can resemble an airplane landing, a swarm of wasps, the surf, the play of glasses. Sonorous works have no melody or harmony. We cannot sing them, we often cannot even determine the pitch of the sounds that make up the blocks of sound: It is a stream of changing timbres.

https://www.youtube.com/watch?v=8xbs0RzVqpY - - Youtube to mp3

By the way: The word "sonorica" comes from the Latin sonorus, "sonorous", "echoing".

https://www.youtube.com/watch?v=FMwuNjbzo9w - Youtube converter

• Serialism - a compositional technique in which the rules of dodecaphony (building up a series of 12 non-repeated sound events) apply not only to pitch, but also to rhythm, the way the notes are articulated, and volume.
• Sonorica is a major movement in music of the second half of the 20th century that emphasizes thinking in terms of tonal blocks, colorful sounds, rather than single notes.

Examples:

Karlheinz Stockhausen, Pierre Boulez, Bruno Maderna, Luciano Berio

Read next:

Electronic music