Cornelius Cardew has said: 'There is much more in the score than what is used in the production of a sounding performance, much more than what is communicated through a single performance'.

When a multiplicity of solutions to any specific musical problem is intrinsic to a work, then this work must be heard in several different interpretations so that we might come to know its landscape. If all the possible solutions were presented simultaneously, the result would be an undifferentiated mass of sound, hence Cardew 'The criterion of a good performance is not completeness (perfection), but rather the lucidity of its incompleteness... The music itself on the other hand lies in the score; the score is the composition and as such has its own value apart from any particular interpretation.

What is happening is that the composer is becoming the performer once more - as in the days of Bach's organ improvisations, and Beethoven's piano performances and improvisations. Or else, during the reign of the symphony (say from Mozart to Mahler), the composer simply became the conductor - Beethoven, Berlioz, Mahler and finally, Boulez. Composers have always performed, and they still do. I cannot see why this should cause critics such concern: the only possible answer is that most critics are deplorably uninformed as to recent developments in music. I grow tired of repeating: 'What nonsense! Where is the revolution?'

There has been no revolution in recent music. Composers now improvise and leave a large part of what they formerly did to the performer mainly in response to the impact of electronic technology and the concept of teamwork on music. Were our complaining critics only to pick up a book on ornamentation in Seventeenth, Eighteenth and Nineteenth Century music, they would be surprised to find how little resemblance the Bach or Beethoven they know bears to the music they would have heard played and directed by the composers themselves.

John Cage, whose work is seminal in this century, led the way to the breakdown of rigid, fixed scoring in the early 1950s. All of Cage's innovations were transported to Europe by composers like Stockhausen and Boulez. These men aestheticised the whole business of writing music, creating works which are indeterminate as to their form (one may play unit A, B, C, D, etc. in whichever order one wishes) but completely worked out as to the details of pitch, tone colour, rhythm, metronomic speed and so on. Most people have preferred this way of treating performer collaboration because it is easier to digest (audience), it can be analysed (critic), and it has a more obvious relation to the mythologies of our musical past.

Many composers (including Stockhausen) have now formed small improvisation ensembles in order to explore the act of music making in the present tense. The accent is on the 'now', 'here', 'at this moment', rather than on the relation of beginning to end, and all the other structural principles which pervade the older concept of what a work is or should be.

Composers are starting to bring the time of a work back into the time of everyday living, just as Cage brought the sounds of everyday living into the content of his work in the 1940s and 1950s. Cage also pioneered the concept of real-time in such works as Variations 4, which record live audiences at several different points and play them back to the audience in a hall (these concerts go on for several hours at a time). Into this category fall numerous composers and groups: Cornelius Cardew (AMM); Frederick Rzewski (Musica Electronica Viva); Robert Ashley ('Once' group) and La Monte Young's Theatre for Eternal Music.

I have said elsewhere that the greatest distinction between different kinds of music turns on whether or not an instrument attached to a loudspeaker via a microphone is used. Classical music can be redefined as music made without attachment to a loudspeaker.

Composers are just now beginning to get a feeling for music existing in space, and the ability to manipulate that space aurally. They may well enter the field of architecture - for just as architects plan the visual design, 'sound architects' will plan the aural situation of any room, hall or building. Take for example Terry Riley's Time Lag Accumulator, recently installed in a New York art gallery. The installation consists of numerous hexagonal boxes, one within the other. There are many doors through which members of the public may enter the first, outer chamber. Innumerable microphones pick up the sounds from the outer chamber and feed them into the inner chamber via a delayed replay system. When a member of the public enters the inner chamber, he hears the sounds he was making (talking, coughing, shuffling etc.) plus the sounds of others.

Another clear example of space manipulation was La Monte Young's installation at the Heiner Friedrich Gallery, 6-19 July, 1969, his first 'Dream House'. Of it Young said: 'The environment in sound and light at Galerie Heiner Friedrich will be continuous during the hours 10 to 18 and later on some days, Monday through Saturday. Visitors who wish to hear us sing with the continuous frequency environment may telephone the gallery to find out if we are or expect to be singing on that particular day and during which hours... Time is so important to the experiencing of and understanding of our work that the installation for two weeks duration at Galerie Heiner Friedrich will provide the most realistic environment for its realisation we have so far encountered. This presentation will be our most complete public statement to date.'

Perhaps composers will soon be placing sound generators in one part of a room, and using acoustic reflectors and sound absorbers to alter the sound shape of the room. This is one possibility in which I am personally very interested.

In the case of my own work EAR (to be published shortly by OTHER VOICES), I notice that what happens is something completely without reference to critical systems. The critic has to take part in my work if he is to hear anything at all, and even then he will only hear certain sounds within his own head and observe various actions with their hands, heads and ears. Is there an audience for this work? How can criticism function if nothing is shared?