He graduated in 1942 from the Eastman School of Music in Rochester, N.Y., where he studied with the acclaimed composer Howard Hanson. He also studied at the Juilliard school in New York and with the celebrated French composition teacher Nadia Boulanger.
An outstanding pianist, Mr. LaMontaine held the piano seat in New York’s NBC Orchestra, under conductor Arturo Toscanini, from 1950 to 1954. He also accompanied several opera singers, including Price, in recital performances.
When Price reprised Mr. LaMontaine’s “Songs of the Rose of Sharon” in Washington in 1960, Hume wrote in The Post that the songs “have not lost an ounce of their passionate, languorous beauty, a delighting in love that has few if any equals in the world of music.”
When Mr. LaMontaine joined Price and other performers onstage, Hume wrote, “the audience quite literally refused to let any of them go, including the young composer, until they had worn a path from the door to the center of the stage and back again.”
Among Mr. LaMontaine’s Christmas-season works for the National Cathedral, “The Shaephardes Playe,” was shown nationally on ABC television in 1967.His symphony “Wilderness Journal,” drawn from the writings of Henry David Thoreau, was premiered by the NSO at the Kennedy Center in 1972.
An ambitious composition about the Revolutionary War, “Be Glad Then America” — which included a vocal part for the folk singer Odetta — debuted in 1976 with the innovative conductor Sarah Caldwell leading the Pittsburgh Symphony Orchestra.
Mr. LaMontaine, who had no immediate survivors, continued to be a prolific composer well into his 70s. He was at the keyboard for the debuts of three piano concertos in the 1980s, and some of his chamber works continue to be performed. If his symphonic music has not yet captured the audience that once seemed promised to him, Mr. LaMontaine was unconcerned.
“I’ve never spent a lot of time on publicity or anything like that,” he said in 2003. “I just want to write my pieces.”