Tom Johnson, a composer and critic whose Village Voice columns documented the renaissance of avant-garde music in downtown New York during the 1970s, and whose own compositions embraced minimalism and mathematical clarity, died on Tuesday at his home in Paris. He was 85.

His wife and only immediate survivor, the performance artist Esther Ferrer, said the cause was a stroke following long-term emphysema.

Mr. Johnson was a young New York composer in need of income in 1971 when he noticed that the exciting performances he heard downtown were not being covered by local news outlets. He offered to write about the contemporary music scene for The Voice, and he soon began a weekly column.

It was an opportune moment: Art galleries, lofts and venues like the Kitchen were presenting concerts by young experimenters like Steve Reich and Meredith Monk, and Mr. Johnson became the emerging scene’s chief chronicler.

“No one realized at the time that one of the most significant genres of serious music of the century was developing, a genre that was to become known as American minimalism, and which would find imitators all over the world,” he wrote in 1983, in his final Voice column.

He charted the rise of musical minimalism, including the transformation of the local composer Phil Glass to an international phenomenon, but he also documented radical work by lesser-known figures: Yoshi Wada, who sang through massive plumbing pipes; Jim Burton, who amplified bicycle wheels; and Eliane Radigue, who created uncanny drones on a synthesizer.

“I learned some interesting things about gongs on May 30 at a Centre Street loft concert,” Mr. Johnson wrote of a 1973 show by the young composer Rhys Chatham. “That gongs have many different pitches, most of which don’t make much sense in terms of the overtone series; that different tones stand out, depending on how the gong is struck; that when a gong makes a crescendo, a wonderful whoosh of high sound streams into the room; that loud gongs vibrate the floor in a special way and put an odd charge in the air; that listening to gongs, played alone for over an hour, is an extraordinary experience.”

By describing such outré happenings in matter-of-fact, observational prose, Mr. Johnson provided a national readership with access to performances that might be attended by only a dozen listeners, and possibly never heard again. He saw himself as a participant within the scene, and he provided such generous coverage that he became known among composers as “Saint Tom.” His writings, collected in the 1989 book “The Voice of New Music,” offer a uniquely intimate portrait of a galvanizing musical era; for one memorable column, Mr. Johnson sang in the chorus for a rehearsal of Mr. Glass’s landmark opera “Einstein on the Beach.”

But Mr. Johnson was also unafraid to critique concerts that he thought didn’t work conceptually, or note when he fell asleep. Some columns took formal risks. He once devoted a thousand words to reviewing “one of the most impressive performances I ever heard”: the warbling of a mockingbird on Long Island.

He was among the first writers to begin using the term “minimal” to describe much of the repetitive music he heard, and he applied the word to his own compositions, such as the hypnotic 1971 work “An Hour for Piano.” “I have always been very proud of it, because that’s the only word that really describes what I’m doing,” he said in a 2014 interview. “I always worked with reduced materials and tried to do simple music.”

In Mr. Johnson’s dryly postmodern “Four Note Opera,” a quartet sings arias about arias — on only the notes A, B, D and E. The first performance, in 1972, had an audience of about 10 people; the opera has since received more than 100 productions. For “Nine Bells” (1979), he walked among a grid of suspended burglar alarm bells for nearly an hour, chiming them in predetermined sequences, a feat of geometric precision and physical exertion.

In the 1980s, he immersed himself in Euclid’s number theories and Mandelbrot’s fractals, eager to find new musical structures. His compositions of this period include “Rational Melodies,” a series of entrancing miniatures built from simple, symmetrical patterns, and “The Chord Catalog,” a methodical two-hour presentation of the 8,178 chords that can be found in a single octave.

Though undergirded by his mathematical exercises, Mr. Johnson’s music is visceral and intelligible — and, often, deliberately predictable — rather than abstruse. “There is something particularly satisfying about projects where the logic (the music) seems to arise naturally from some discovery outside of myself, and where everything comes together with a minimum of tampering (of composing),” he once wrote.

Thomas Floyd Johnson was born on Nov. 18, 1939, in Greeley, Colo., a small farming community. His parents, Harold Francis Johnson and Irene (Barber) Johnson, were teachers.

When he was about 7, Tom began playing the piano intermittently, and he found his passion for music at age 13 under the tutelage of a local piano teacher, Rita Hutcherson, who also encouraged his composing.

Though many of his peers attended nearby universities, Ms. Hutcherson urged Mr. Johnson to apply to Yale, where he received a bachelor’s degree in arts in 1961 and a master’s in music in 1967. As an undergraduate, he took a seminar with the prestigious composer Elliott Carter and dabbled in 12-tone composition, the lingua franca of the musical academy, but he found himself embracing repetition and stasis instead of cerebral complexity. He moved to New York in 1967 to study privately with the experimental composer Morton Feldman, who helped him find his artistic voice.

After documenting the New York scene for The Voice but struggling to have his own work performed, Mr. Johnson decamped to Paris in 1983, where fresh opportunities awaited, as European audiences were newly drawn to the American avant-garde. There he remained a prolific writer, theorizing about his own music in several books. He had been publishing his own scores since the 1970s, and he maintained an active web presence with a video series elucidating his music.

His major works have included the satirical “Riemannoper,” based on excerpts from a famed German music lexicon, which has received more than 30 productions; and a more serious oratorio drawing on the writings of the German dissident Dietrich Bonhoeffer. But much of Mr. Johnson’s output remained resolutely abstract, including an orchestral work that lays out a sequence of 360 chords and a series of recent pieces that systematically explore various rhythmic combinations.

Mr. Johnson’s marriage to the choreographer Kathy Duncan ended in divorce. He married Ms. Ferrer in 1986.

One of Mr. Johnson’s compositions has become canonic in the double-bass community: “Failing” (1975), a fiendishly difficult and hilarious exercise in which a soloist is instructed to bow tricky passages while reading a lengthy text aloud that self-reflexively comments on the music. “These pieces all had to do with making music as real life,” Mr. Johnson said of the work in a 2020 interview. “I wanted the performer to confront an unknown situation and deal with it as well as possible in a one-time-only context.”