There’s something strange about applauding at the end of very quiet music: it is counterintuitive to make more noise clapping than the performers made during the actual performance. But the appreciative Kings Place crowd in Hall Two knew the drill, and this concert of “Some Recent Silences”, as it was billed, proved justly popular. Cellist Anton Lukoszevieze’s ensemble Apartment House delivered delicate, sensitive performances, exposing us – courtesy of Tim Rutherford-Johnson’s carefully assembled programme – to a range of provocative, quiet music.

It’s not news that music is more than just sound. Performing is always something bigger than that; even in a piece of music played at a conventional volume, watching a performance is a key element of the experience. But in a programme like this one, where the noises frequently court silence, watching the performers in action becomes even more crucial. Blink, and you miss it. Is that noise coming from the cello, or is it someone rustling a programme? Did the clarinettist just cough, or was it only an audience member? Did I actually just hear anything at all, or did my mind make it up?

Though the seven pieces successfully demonstrated the range of different things that music can be at low volume, what linked them all together was the way they demanded close, edge-of-seat attention. Facing the real risk of missing out on actually hearing anything if our focus wavered, we in the audience were made to do a lot of work here – and I’m in no doubt that this enforced lack of complacency made the concert a far richer experience overall.

Thanks to Apartment House’s soft pencilwork, the programme began with one of the deepest silences of all. The four players, co-ordinated by the flick of a stopwatch from pianist Philip Thomas, were required to start G. Douglas Barrett’s A Few Silence (London, 22 September 2013, 16:00) by transcribing the sounds of the room. After a few minutes doing so, they played their transcriptions. The loudest noise was Thomas gently brushing the floor. Listening closely, I also heard soft taps from Lukoszevieze, and the occasional breathy sound emanating from the environs of clarinettist Tom Jackson. Vocalist Lore Lixenberg’s contribution was lost to me, but given that she was sitting on the other side of the room, I doubt she’d been able to hear me, either, when she was transcribing.

Of the longer pieces played, the next quietest was Charlie Sdraulig’s close, which (like Douglas Barrett’s piece) required the musicians to respond live to their surroundings, the sounds of the performance influencing them as they proceeded. Towards the end, Lixenberg completely covered her mouth with her hand, an amusingly appropriate gesture given the quietness of it all. The concept and the process – as well as the sounds that did happen – made listening in on this a strange, gripping experience.

Perhaps rather different in concept, but similar to Sdraulig’s piece for its soft, deeply calming air, Mathias Spahlinger’s 128 erfüllte augenblicke made further experiments with giving choice to the performers: of the 128 seconds-long fragments, any number may be performed, in any order, any number of times. The silences which separate each fragment are, according to Rutherford-Johnson’s note, “not part of the music”, but absences from it. This distinction seemed arbitrary on first reading, but it prompts some seriously peculiar questions on where exactly music can be said to begin. So, in another contrasting way, did the other “classic” piece on the bill from 1975: György Kurtág’s miniature Quarreling 2 (Dumb Show), in which the pianist plays a short piece without actually sounding any of the keys.

If the remaining pieces weren’t quite as quiet, they provoked and delighted all the same. Gregory Emfietzis’ DIY 1: the pianist and the lamp, despite a programme note by the composer entirely about neurology, saw the ever-willing Thomas wage a sort of silent war with a lamp, underlining music’s potential closeness to performance art. Ben Isaacs’ allone, on the other hand, was the most conventional piece, appearing fully and conventionally notated, but again its soft sounds drew us in to listen closely.

Veteran quiet composer Michael Pisaro’s piano piece Fade ended the set in fairly conventional fashion as well, with Thomas facing less bizarre demands than in most of the other pieces. Occasional notes are played at mid volume, and then repeated slowly, getting progressively quieter. This simple concept requires the most meticulous of realisations, and while Thomas was up to the task it was hard not to notice slight lapses among all the gradual fadings-out.

But then, my ears – and probably the rest of the audience’s too – had just been doing some serious exercise, in trying to make sense of all these fragile, barely-there worlds of sound. This concert was a reminder of the value of close listening: by making us work to hear it, it proved that it was worth our full attention.