On Tuesday, September 28, at Jordan Hall of the New England Conservatory of Music, Stephen Drury’s Callithumpian Consort revisited works of earlier decades by three then-avant garde composers: Robert Ashley, born in 1930, Alvin Lucier, born a year later,  and Christian Wolff, born in 1934. The composers are all alive and definitely kicking — Wolff was in residence at the New England Conservatory last March,  producing numerous lectures, master-classes, and performances, including some premières. Both he and Lucier were present at this concert to acknowledge enthusiastic applause by a generally young audience. Surprisingly, only one or two others present (including your reviewer) were of an age to have heard these works when they were written.

Lucier and Wolff have long been a presence in Boston and New England. Lucier has taught at Brandeis and, since 1970, at Wesleyan University; he and Ashley, who was based at the University of Michigan and is most famous as the director of its ONCE Group and its Festivals of the ‘60s, were founding members of the Sonic Arts Union that toured widely for ten years (1966-76). Wolff taught Classics at Harvard and, from 1971 to 1999, both Classics and Music at Dartmouth College. Describing himself as an autodidact in music, he was a member of the so-called “New York School” of composers that included John Cage, Morton Feldman, and Earle Brown.

The “Thumps” comprise a core group of twelve, adding other players as needed, who have dedicated themselves to contemporary music for several years,. Currently they are performing an enormous amount of music in various venues, with very little time between concerts. Rather than seeming exhausted, they are playing at the peak of their skills and sensitivity both to each other and to the music. I am sorry that they are too numerous to identify here, but all were commendable. Drury was present,  moving music stands on stage on one occasion, but not conducting even the large ensembles. The players’ “concert dress,” mimicking Drury’s own, is blue-jeans and white shirts and blouses (with high heels for the women). Strangely enough, this adds to the seriousness of the enterprise, or at least the earnestness.

The performances of the chosen works, which all depend for their expression on verbal directions from the composers to the performers as well as on the visual contents of the scores, were uniformly excellent. Robert Ashley’s “In memoriam . . . ESTEBAN GOMEZ” (1963), which opened the program, is written for four unspecified instruments — in this case, a string quartet (Miki-Sophia Cloud and Ethan Wood, violins, Gabriela Diaz, viola, and Benjamin Schwartz, cello). The score, published in 1990, is a one-page document containing performance directions and a circle constructed of dots. Each player assigns musical parameters (pitch, intensity, timbre, and density) to four quadrants and also a unit of time to each dot. They must agree among themselves on a core sonority, with the understanding that it should be one indistinguishable whole,  and with which the work must begin. There’s more to it, of course, all in the program notes. Without knowing all that, it is still an arresting piece combining stasis and subtle change. For this version the players chose to begin on a single very soft pitch, I think an E, the upper open string of the violin, which was held steadily throughout. The whole piece was a palindrome, in that the three open fifths sounded in turn below the initial pitch were sustained, and then similarly subtracted, ending on the same single pitch again. Sounds dull? Not on your life! I for one was on the edge of my seat, wondering what subtle variation would come next, for the players had many choices: bowing (long or short), vibrato (fast or slow), sliding the pitch up or down, etc.

Alvin Lucier’s Crossings was written much later (1984), but has a surprisingly similar effect, because one listens intensely, discriminating the pitches and timbres of sound frequencies ranging from 25 to 4,186 Hz (cycles per second). It is composed for a specific mixture of sixteen instruments and a slow sweep sine wave oscillator, requiring in addition a frequency counter, amplifier, loudspeaker, video camera and two video monitors. The idea is a simple one, and here I must quote from the deft program notes by Adam Roberts: “As the sine wave oscillator produces a steadily rising glissando electronically, selected instrumentalists join in periodically at specified frequencies. For example, between 35 and 38 Hz the double bass plays alone while between 177 and 194 Hz the double bass, bassoon, bass clarinet 1, and horn are present.” That is, the piece proceeds slowly through the range of Hertz frequencies, adding and subtracting instruments until only the violins and piccolos are playing at the top. The players are instructed to “adjust dynamics to produce the strongest audible beating between the sustained sounds and those of the rising wave.” That is, the oscillator rises first, and the instruments edge up to it, listen for the beats, and then blend. Again, fascinating and engaging musical sounds, even if designed as sonic play.

Christian Wolff’s Braverman Music (1978) is dedicated to the memory of Harry Braverman (1920-1976), an active Socialist and one-time editor of Grove Press. It is music of an entirely different sort; there are composed short sections of printed music, but the same in that how this music is performed is aleatoric — not all the sections need be played — and depends on extensive directions. It requires a minimum of four players (or four hands), who must encompass a range of F1 to D7, but most else is left to the players’ discretion. Much of the music is homophonic and consonant, but there are brief excursions into counterpoint. Especially charming were those for bass clarinet (Rane Moore) and viola or violin (Gabriela Diaz). As performed here, the ensemble comprised thirteen players (two flutes, oboe,  two clarinets — one doubling on bass clarinet — bassoon, horn, trumpet, tuba, two violins — one doubling on viola — cello, bass, harp and piano) distributed in two U-shaped seatings side-by-side, so that several were sitting with their backs to each other. If there were two of the same instruments, they were in different U’s; sometimes they played the same music, and sometimes they didn’t. All in all, a remarkable tour-de-force of superb ensemble playing. Think of all those decisions that had to be made! Wolff seemed very pleased with the results, as well he should be.

Mary Wallace Davidson has directed the music libraries at Radcliffe, Wellesley, Eastman School of Music, and Indiana University. She now lives in the Boston area.