NEW CANAAN — Seated at the piano in the Adrian Lamb Room of New Canaan Library, Professor Gil Harel, of Baruch College, keyed the sparse notes of the iconic opening lines of Miles Davis’ 1959 “So What.”

“It’s like minimalism, isn’t it?” Harel asked the sizable crowd on Tuesday night come to see his lecture “From Bebop to Modal Jazz — Rapid Musical Developments in Post-World War II America.”

Harel played Davis’ song, part of a period of the musicians work that would come to epitomize the subgenre modal jazz, to illustrate the substantial, and at times shocking, ways in which American music developed in the span of two short decades following the war, often to an alienating effect.

“This is coming after the realization of all the horror, all the death, all of the carnage and destruction, the evil which was witnessed,” Harel explained, of bebop and subsequent developments in jazz. The result, Harel said, was a music more full of dissonance and utilizing gloomier minor chords than earlier Big Band and swing sound that had previously dominated the radio.

Harel’s lecture centered on saxophonist Charlie Parker, the heroin-addled king of bebop, a fast-paced, highly complex style in which performers shift dexterously between chords and key and long improvisations; trumpeter Davis, whose seminal “Kind of Blue” remains the top-selling jazz album of all time and helped to epitomize modal jazz, which slammed the brakes on bebop in favor of a more harmonic and repetitious sound; and saxophonist John Coltrane who, with Davis, pushed the boundaries of jazz, ultimately creating some of the genre’s most well-known and challenging recordings.

Despite their breaking down of boundaries, the music of these three musicians, Harel said, was often cause for debate during their lifetimes.

Parker’s was a polarizing sound at the time of his death, in 1955, at 34, and preempt a shift away from bebop. The experimentation of Coltrane and Davis, too, alienated listeners. Later in his career, Davis refused to play his earlier hits from albums like “Kind of Blue” and “Sketches of Spain,” opting instead for experiments in rock and world music. Before his death in 1967, Coltrane’s “Om,” which incorporated chants from the Bhagavad Gita, was at first rejected by critics for its apparent disorganization and disorganization.

But according to Harel, Coltrane, like Davis and Parker, are significant precisely because they were impelled toward experimentation and toward “music that is so virtuosic, in fact, that’s it’s kind of virtuosic to the point of exclusivity.”

justin.papp@scni.com; @justinjpapp1