At the end of October the Barbican Arts Centre in London hosted the 'Elektronic' Festival - a festival dedicated to the pioneering, avant-garde composer Karlheinz Stockhausen and some of the artists who have followed in his wake including Richard D James, Bogdan Raczynski and Talvin Singh. Stockhausen is now 73 and still composing. He was one of the world's first composers of electronic music. In the early 1950s he was the first composer to synthesize new sounds by combining individual sine waves - the 'sounds within sounds', the sonic 'atoms' that when fused together give a sound its unique quality. His works still sound wild, radical and new and in these articles composer and writer Robert Worby looks at Stockhausen's legacy and presents detailed notes on his early electronic music.

Bach - Haydn - Mozart - Beethoven - Brahms - Wagner - Schoenberg - Webern - Stockhausen. As the story of Western music unfolds and the history books are written we find Stockhausen's name written in the most recent chapters. A direct linear thread traces out the Post Renaissance tradition and when we get to the turn of the 21st century ..... there is Stockhausen writ large. His name first appears in the middle of the 20th century, just after the Second World War and around about that time several other elements in this story also appear - the tape recorder, vinyl records, the teenager and pop music. Stockhausen's career runs almost parallel to that of pop music but whereas pop music has remained essentially rooted in the essence of its origins Stockhausen's music has transformed, developed and has continuously changed in its methodology, its procedures and its sound world. In every piece that he has composed he has virtually re-invented the idea of what music is and how it comes into being.

Pop music exploded into the world in the 1950s because the technology of sound recording and vinyl records allowed the music to be produced cheaply and distributed widely, and the post-war economic boom created the mass market, and invented the teenager, to avariciously consume it. In essence the music has remained the same since those times. It usually relies on a pulse, or a feeling of pulse, regularly divided, usually into fours, with an uncomplicated diatonic melody that can easily be recalled and identified. Of course, not all pop music follows this simplified model but generally, it is functional music, made for entertainment or diversion and not usually for intense, attentive listening or serious analysis. It is often music that accompanies some other activity - dancing, driving a car, housework, homework or maybe doing nothing in particular. It often sits easily in the background and is quite happy there.

Stockhausen's music, on the other hand, interrupts other activity. It disrupts, it demands attention and it necessitates concentration. It is not really possible to be doing something else while listening to this music. It requires detailed listening and analysis, it exacts effort and commitment. This music empowers the listener who cannot but take part in the musical process. When engaged with Stockhausen's music, the listener's skills are exercised, developed and enhanced. We cannot simply hear this music because hearing is passive, a physiological phenomenon; we have to engage the hearing along with intellect, emotion, knowledge and all the powers we posses. Listening needs practice just as a performer practices. It is an activity and Stockhausen's music encourages us to be active as well as facilitating the development of the skills needed to participate. And, these skills are transferable, they can be taken and applied to other listening situations whether it's Mozart, The Beatles or Percy Faith and His Orchestra. Even walking down a busy street, sat on a bus or a remote mountain top the developed listening skills raise consciousness and awareness encouraging creative aural connections between seemingly disparate elements.

The painter William de Kooning once said, 'The past doesn't influence me, I influence it.' On the surface this may appear to be an incredibly arrogant statement but there is more than an element of truth here and, although Stockhausen has never made this declaration, the idea could well apply to his work. Having heard one of his piano pieces or a work like GRUPPEN or HYMNEN or almost anything he has composed we come away with new ears; something in our lives will have changed and, if we are open to these changes, new ways of listening will have been discovered, new structures will have been observed and new ways of thinking about music will have been acquired. Stockhausen's music does not exclude other musics, it is not the case that if you listen to Stockhausen you cannot listen to, and enjoy, any other music; indeed he has written of TELEMUSIK that he wanted "to take a step further in the direction of composing not 'my' music but a music of the whole Earth, of all countries and races." His music asks questions, raises doubt, makes us search and investigate. It's not easy; it's not meant to be easy and the listener will not necessarily like everything that is heard. Stockhausen hasn't written this music to make himself popular, he doesn't have to be 'commercial' and he has no obligation to please critics, publishers or record companies.

The guiding light of Stockhausen's mature works has been serialism, a compositional methodology that grew out of the intensely chromatic music of the late 19th century and the twelve tone, atonality of Schoenberg. By the turn of the 20th century the idea of music being rooted in a particular key, with a strong pull towards a fixed centre, had given way to a system where all the notes of a scale had equal value or attention. This was the beginning of the idea that music was about sound not just notes or tunes or harmony. Melody as the primary structural element, as the most important feature of the music, gave way to the idea that all the characteristics of sounds could have equal importance. The duration of a sound (the parameter that articulates rhythm), its volume and its timbre, (its colour, what the sound actually was - piano, cymbal, sine-wave) became as important as pitch, notes or melody. And because composers no longer had tunes around which to structure their pieces they had to find other ways of putting sounds together. For Stockhausen, serialism was the way to go. In 1971, having worked with this method for twenty years, he said "Serialism is the only way of balancing different forces. In general it means simply that you have any number of degrees between two extreme that are defined at the beginning of a work, and you establish a scale to mediate between these two extremes. Serialism is just a way of thinking."

In the mid 1950s Stockhausen added the parameter of physical space to the list of sonic characteristics that could be incorporated into the compositional process. Works like GESANG DER JUNGLINGE, GRUPPEN (for three orchestras), CARRE (for four orchestras and choirs) and all of his electronic works after the two studies exploit the fact that sounds are located in space, that they can move in space and that humans have two ears to detect where sounds are located and, if they are moving, the direction and speed of the movement. The listener can hear all of these things in Stockhausen's music and the way he has put together the disparate musical elements is there for discovering.

The influence of Stockhausen's work and the possibilities he has offered the listener are immense. He has challenged the idea of what music can be, time after time after time, and he has re-written and re-defined the 'laws' of composition with almost every piece he has composed. The rules that, for hundreds of years, said 'this is how music is written', have been torn up. He has liberated the whole world of sound and this, in turn, has empowered and liberated the listener.