John Cage once commented that:

‘If something is boring after two minutes, try it for four. If still boring, then eight. Then sixteen. Then thirty-two. Eventually one discovers that it is not boring at all.’

This year’s Cut and Splice contemporary music festival at the ICA, produced by Sound and Music and BBC Radio 3, prominently featured the composer collective Wandelweiser, which appears to take this maxim as an aesthetic starting-point. The collective performed nine works over the course of the four-day festival, and, while the performances varied widely in concept and effect, all shared a fascination with exploring the potentials of silence, celebrating sound as it is.

Jürg Frey, whose two paragraphs on his piece ‘Brachland’ win the prize for most provocative programme note, possibly ever, commented that ‘No creative act is needed’ in his compositional process: ‘There is a silence in the depths of sounds that I respect’. It is striking – perhaps Cagean, though – to deny the imaginative role of the composer so forcefully. And as the composer’s role is de-emphasised, the role of the listener grows. In a piece like Radu Malfatti’s ‘Darenootodesuka’ (Japanese for ‘Whose sound is it?’), it is as much up to the audience to hear as it is to the musicians to play. In this extremely gentle composition, six musicians occasionally contribute quiet sounds, with long silences between. It took me on a strange mental journey where every time I stopped looking at the performers I became completely uncertain whether the sounds I was hearing were actually being produced by them, or whether they were ambient noises, or whether I was just imagining them. I was, as far as I was concerned, as active a participant in the piece as the performers. This was more literally the case in Marcus Kaiser’s ‘Unterholz’, every performance of which is filmed and then layered over subsequent performances, giving every performance and every audience member some small role in the work’s ongoing creation.

I wouldn’t suggest that each of Wandelweiser’s works was a complete success. Manfred Werder’s ‘2010 (1)’ may have pushed things too far, lasting thirty minutes but possibly containing as many notes as musicians. And there were moments during these long pieces when I did wish the ICA had some more comfortable chairs. But to describe any of the Wandelweiser repertoire as boring would be – to push Cage a little further – unimaginative. There are very conspicuously more questions than answers in all of this music, but I struggle to see what’s wrong with that. Wandelweiser are radically unpatronising to their audience.

They were joined at Cut and Splice by another uncompromising collective, the Ireland-based group Grúpat. While they perhaps seemed a little more loosely connected than Wandelweiser, the key element which all their compositions shared was a commitment not uniquely to music, but just as much to visual or performance art. Violetta Mahon’s ‘Dream Diaries 1988-2008’ required the brave and artful Ensemble Ascolta to throw paper aeroplanes while pacing the room, intone passages of literary criticism in unison, and watch films on laptops wearing headphones.

All of Grúpat’s other contributions to the festival featured the singer Jennifer Walshe, whose virtuosity was unfailingly impressive. During various pieces she was made to play the ukulele, the violin and the tin whistle, to manipulate live electronics, and to interpret a spectacular array of graphic scores using extended vocal techniques. Alongside moving performances of eccentric works by Turf Boon and Ukeoirn O’Connor, one highlight was ‘The Wasistas of Thereswhere’, a piece by The Dowager Marchylove, who is the transvestite musical flâneur alter ego of performance artist Niall Quinlan. Involving some breathless recitation of text, multiphonics on a tin whistle, a kazoo, and some insanely fast Irish folk singing, the sound is built up through electronic looping to create a dense beautiful texture of white noise, like a heavenly radio – which is then suddenly turned off, leaving Walshe alone, singing her mad nonsense Irish song to herself. Here, and in a few other moments, the Grúpat performances transcended their slightly self-conscious impenetrability and created fascinating sonic/performative pieces.

The festival also featured a visual exhibition by members of Grúpat in the ICA Studio, during which the audience was ‘strongly encouraged’ to eat some traditional Irish tea brack. The display was useful in fleshing out some of the composers’ profiles and giving a better sense of Grúpat’s truly broad perspective. It was also fascinating to learn about the mysterious figure of Caoimhín Breathnach, a reclusive ‘outsider artist’ whose works are slowly starting to draw attention since his death in 2009, when a lifetime’s artistic output was found in his cottage. One practice of his was apparently to record sounds onto tapes and then bury these tapes, before digging them up again in accordance with the astronomical calendar.

The story of Breathnach may push the boundaries of eccentricity about as far as they can reasonably go, but ultimately what his odd ritualistic treatment of tapes offers is yet another completely original interpretation of music. There are perhaps few discernible similarities in artistic approach between the members of Grúpat and Wandelweiser, but what they presented together at the Cut and Splice festival was a real sense of the broadness of ‘music’ as a category, its openness to any number of interpretations or definitions. In ‘La Solennité des Silences’ Eva-Maria Houben of Wandelweiser found music in silence. Violetta Mahon found music in having a paper aeroplane thrown at a cellist. None of them can have been wrong.

Extracts from the Cut and Splice festival can be heard on BBC iPlayer till Sunday 13 November.