The music was quiet at last Sunday night’s electro-acoustic-improvisation concert at Durrell Hall at the YMCA in Central Square, but there was still plenty to hear. The duo of Keith Rowe and Toshimaru Nakamura barely rose above a whisper, and the group nmperign (soprano saxophonist Bhob Rainey and trumpeter Greg Kelley) with percussionist Le Quan Ninh remained at pianissimo through most of their opening set. But they rewarded attentive listening with sophisticated music that challenged ideas about silence, energy, dynamics, and melody in improvised music.

The Boston-based nmperign have found a perfect collaborator in French percussionist Ninh. Using stones, sticks, even a pine cone, Ninh elicited an astonishing variety of sounds from a bass drum set face-up in a frame. Rainey and Kelley likewise used unconventional techniques — Kelley scraped his trumpet with a metal plate; Rainey blew into his mouthpiece cap. But technique was incidental — the sounds created and the way in which the players organized them mattered, and these three are some of the best spontaneous organizers of sound working today. Their piece opened with isolated clicks, scrapes, and tones, but they slowly drew together into a richly layered, unified sonic mass. Textures and colors shifted within it, as long pulses and sudden bursts of short quick tones rippled through the assemblage. The outline of the collective sound pushed in different directions as a marvelously organic, evocative fabric emerged. Dancers Yukiko Nakamura and Pascal Delhay performed simultaneously with the instrumentalists, offering an expressionistic counterpoint to the music’s restraint.

Nmperign and Ninh sounded like the Peter Brötzmann trio compared to English tabletop guitarist Rowe and Japanese electronic sound artist Nakamura. Their short set hovered on the brink of inaudibility for its entirety. Nakamura’s no-input mixing board generated little pinpricks of sound and high-pitched whines that materialized and evaporated, while Rowe switched a cheap transistor radio off and on, placed a personal fan on a microphone to generate a low hum, and performed other low-tech sound manipulations that created diffuse washes of noise. The biggest event in the set was a series of sharp beeps that sounded like a smoke detector whose batteries were running down. Their improvisation opened a window on a continuous spectrum of sound without beginning or end. On their recent CD, Weather Sky (Erstwhile), Rowe and Nakamura achieve a numinous power through the slow accumulation of noises. But this performance expired in silence before reaching a similarly transcendent state.