In one of the most pitifully attended concerts I’ve ever witnessed in Vienna, last weekend saw a deserted Porgy & Bess play host to the first gig in seven years by electroacoustic improvisation quintet Efzeg. The meagre turnout was probably inevitable, given that it was a hot Sunday night and that this music is not exactly a crowd-puller at the best of times; but it was also unfortunate, since what we had here was a reunion gig (oh, how I do love reunions) by a group containing some of Europe’s leading exponents of the electroacoustic genre.

I missed Efzeg the first time around, of course, which makes their 2012 reformation all the more pertinent. I’ve long admired guitarist Martin Siewert’s work, though, having seen him play both with avant rock unit Heaven And and in a trio with saxophonist Mats Gustafsson and turntablist and Efzeg member dieb13 (Dieter Kovacic). Kovacic, meanwhile, turns up in Swedish Azz with Gustafsson, who was a guest at Heaven And’s last Vienna gig. You get the picture.

In marked contrast to those previous, bracing encounters, Efzeg are all about duration, the lengthy accumulation of sonic detail. During the concert, I found myself in an unfamiliar, somewhat disquieting mode of listening. I’m not used to the kind of patient unfolding of sounds that Efzeg present us with; years of close attention to free jazz and improv have conditioned me to enjoy, perhaps even to expect, a succession of thrilling events. Such expectations are clearly not part of the EAI aesthetic. The closest I’ve come would be the few AMM concerts I was lucky enough to see in London in the 1990s, before the deplorable schism that led to founder member Keith Rowe leaving the group. Come to think of it, Rowe’s tabletop style of guitar playing is clearly a direct antecedent of Siewert’s, although Siewert often plays in a more conventional style as well. Anyway, what AMM taught me, and Efzeg reminded me of, was the importance of concentration and close listening as a means of situating oneself within a musical environment.

That makes the whole thing sound like some kind of bloodless sonic experiment; nothing could be further from the truth. Over the course of two longish sets, the group’s four instrumentalists proposed a layered approach in which the saxophone, guitars and turntable each traced their own paths before coalescing into a pulsating and vertiginous wall of sound. The amiable Boris Hauf’s spare, astringent sax was bolstered by the quietly flickering guitar of the studious figure next to him, Burkhard Stangl. On the other side of the stage, Siewert was in abstract tabletop mode for the most part, occasionally exploding into fractured power chords. Next to him, dieb13 was to be seen thoughtfully looking through his records before deciding which one to play next, their soft drones adding layers of snowy interference. Meanwhile, visual artist and fifth member Billy Roisz was using the group’s audio as input for her analogue visual feedback projections. Constantly evolving in response to the shifting textures of the music, Roisz’s bold grids and insectoid patterns provided a hypnotic visual correlative. Taking the music and the visuals together, the overall effect was of a mysterious and unresolved entity stubbornly resisting capture. I sincerely hope the group continues to play live, despite the depressing lack of interest shown in this outing.