Outline the key developments in electroacoustic music, contrasting musique concrète with other electronic music forms.

Electroacoustic music, which encompasses music created through electronic means, has undergone significant development since its inception. Key to this evolution are the diverse approaches to sound manipulation, technology, and aesthetic goals. Among these approaches, musique concrète and other electronic music forms stand out with their unique characteristics. Understanding these differences is vital to understanding the landscape of electroacoustic music.

Musique concrète, pioneered by Pierre Schaeffer in the late 1940s, is characterized by its use of recorded sounds from the real world as raw musical material. These sounds, often called "concrete" sounds, could be anything from everyday noises to instrumental excerpts. Instead of creating musical sounds from scratch via electronic synthesizers, Schaeffer used sounds that are already present in the real world. He manipulated these recordings through techniques like tape splicing, speed alteration, filtering, and layering, creating unique sound textures and sonic collages. The emphasis is on the transformation and organization of the concrete sounds themselves into a musical whole. Schaeffer's early works, such as "Étude aux chemins de fer" (1948), used recordings of train sounds that were cut up, layered, and manipulated. This transforms the sounds from the environment into a musical composition. By manipulating recordings of sounds in this way, Schaeffer and others created entirely new musical forms. The focus in musique concrète is on the source of the sound itself and the potential for its manipulation to create musical effect. The aim was to transform the sounds from the world into something musical.

Other forms of electronic music, particularly those that emerged from the 1950s onwards, often utilized electronically generated sounds as their primary musical material. These sounds are typically created using synthesizers, oscillators, computers, and other electronic devices that can generate waveforms. Unlike musique concrète, which works with pre-existing sounds, electronic music often works with these generated sounds in isolation from the outside world. Composers would often create complex musical textures using sine waves, square waves, and other waveforms as building blocks, with total control over their characteristics (such as frequency, amplitude, and timbre). The focus is shifted from the source sound towards the way sounds can be organized and structured using electronic technology. An early example of this approach can be seen in the works of Karlheinz Stockhausen. In pieces such as "Gesang der Jünglinge" (1956), he combined electronically generated sounds with the recording of a human voice. However, unlike musique concrète, the focus was not just on manipulating the recording but rather on creating a sonic world through various electronic means. He would use techniques of synthesis as a way of creating and organizing the sounds of his pieces. Many studios were created to explore these sonic possibilities of electronic instruments.

Another key development was the increasing integration of computers into the compositional process. Initially, computers were used to generate sounds, but as technology advanced, they became tools for sequencing and manipulating musical material. With early digital synthesis, there was a greater focus on controlling parameters digitally. This allowed a greater complexity in sound design and opened up new possibilities. This shift towards digital technology led to the development of new synthesis techniques, such as FM synthesis and granular synthesis which led to entirely new sound palettes and organizational principles. Many of these techniques are still used in contemporary music creation.

One key difference between musique concrète and other forms of electronic music lies in their relationship to the real world. Musique concrète is rooted in the sounds of our environment, transforming and reorganizing the sounds that already exist. Whereas, other electronic music forms often seek to create entirely new sonic worlds through electronic generation, often avoiding recorded sounds. However, both approaches have contributed to the exploration of new ways of thinking about sound and musical structure and the way sound could be used. They share an emphasis on sound as a primary musical parameter and an interest in exploring its properties. They both represent a shift in how we define music and move beyond traditional practices.

In summary, the evolution of electroacoustic music has led to diverse forms of musical expression, each with its distinct approach. Musique concrète, with its emphasis on manipulating concrete sounds from the environment, stands in contrast to other electronic music forms which emphasize electronic sound generation. Both approaches are essential in understanding the history of electronic music and show different possibilities in using technology for creation.