It is no mistake that one of the most productive periods of cross fertilisation between music and the visual arts coincided with the transformation of the word 'composition'. In the work of Alvin Lucier, and many artists in Open Systems, composition no longer describes internal structure, but establishes a series of parameters determined by external forces - whatever happens within those parameters constitutes the work. It seems to me that Alvin Lucier's work has more in common with Conceptualists such as Hans Haacke, Mel Bochner, Bruce Nauman and Dan Graham than with a Minimalist such as Donald Judd.

Lucier's I Am Sitting in a Room (1969), is a work that explains and reveals its own function and means of operation. Like Haacke's Condensation Cube (1963-5) or Bochner's Measurement Room (1969), it is structurally indeterminate, absorbing its external context and making it part of the work. Each represents aspects of its environment that generally fall outside of human perception. Lucier's setup is simple - two tape machines, a microphone and a speaker. The score is simply a short paragraph in which the performer describes the piece, his motivations for doing it, and what will happen as the piece progresses. It begins by reading aloud and recording the paragraph on the first tape. The recording is then rewound and played back, recording it on the second machine, which is rewound and played back, recording on the first, and so forth. As predicted by his statement, with each iteration the voice loses definition and becomes a distant echo of the original recording. In place of the words, the recordings pick up and emphasise the ambience of the room which gradually corrodes, then rapidly consumes language, recasting the voice and shaping it to the specificities of the space. By its completion, all trace of language has been replaced by rich, sonorous frequencies, modulating in a continuous drone that describes, in the words of Lucier's statement, "the natural resonant frequencies of the room articulated by speech". The voice has not been lost altogether. Only the frequencies that are common to both the room and voice are picked up in the recording, making it a spatial portrait of the speaker's voice, or a description of the room based on abstracted vocal tones. There is no predicting how many generations of recordings are necessary before this effect is achieved, as every space has its own particular sonority and will respond differently, just as each time the statement is read it will have a different cadence and inflection.

It is true that Lucier's work - like Judd's - focuses attention on the specificity and materiality of the object, and on the triangular relationship of object/body/space. But repetition, one of the key themes of Minimalism, plays a very different role in Lucier's work. Judd's objects - or, for that matter, the compositions of Minimalist composers such as Steve Reich - make slight changes to each repetition of a musical or visual phrase in a way that adds variation yet reinforces the notion of a central, inviolate object or motif. For Lucier, or in a work like Bruce Nauman's Dance or Exercise on the Perimeter of a Square (1967-8), each repetition involves a loss of energy, a movement from rationalisation - even domination - of the parameters of the work towards the body's obsolescence in relation to its environment. For Nauman, it is the inevitability of exhaustion and frustration in pursuit of a deadpan, ridiculous, task; for Dan Graham in Public Space/Two Audiences (1976), it is a dissociative, hallucinatory spatio-temporal relation between body and space or between subject and object.

Similarly, in tonight's performance, Lucier explores the relation between sounds generated by the body and sounds generated electronically (In Memoriam Jon Higgins and Wave Songs). By locating the body at the centre of these experiments, these different artists introduce an element that is unstable and will always refuse quantification. The quasi-scientific approaches so widespread c. 1970, particularly in the USA, are remapped onto these non-determinate, non-dominating parameters, demonstrating the absurdity of using a hermetic system to describe lived experience. In fact, when these sets of objective instructions are put into practice, what initially seem like attempts to gather empirical information quickly reveal themselves as critiques of the empirical process. Instead of eliminating results infected by the outside world as corrupted data, in these works the process is allowed to unfold, and fold back on itself. From between these folds emerges the gradual dissolution of fixed objects and possibility that our own subjectivity is not singular or coherent but dispersed and adrift, prompting uncanny fears of, and desires for, an oceanic immersion in sound and space that is beyond the rationale of empirical science.