John Harbison, professor of music at MIT in Cambridge, Mass., last night won the $5,000 first prize in the Kennedy Center/Friedheim Competition for American compositions with a piano concerto that had its world premiere May 12 in Alice Tully Hall in New York City.

From the first note of the concerto, it was apparent that Harbison is among the younger composers who today are writing music that communicates to audiences at first hearing. Cast in two movements, though Harbison says that a middle movement "is housed in both" of the two formal sections, the concerto is openly romantic, using seventh chords that are often left hanging in a manner reminiscent of Francis Poulenc. At the arresting opening of the work, the piano is echoed by the harp, which plays a dominant role throughout.

In writing for the piano and in the orchestral textures that support the soloist, Harbison does not disguise his affection for exquisite sound clothed in undisguised beauty. Robert Miller, to whom the concerto is dedicated, was the superb soloist.

The second prize of $2,000 went to Jacob Druckman of the composition department at Yale University, for "Prisms," the work that won by far the loudest applause from both audience and orchestra. It is a fascinating three-part essay on the Medea legend, making use of music on that subject by Charpentier, Cavalli and Cherubini. Ramon Zupko of Western Michigan University won the third prize of $500 for "Windsongs," a piano concerto.

The other two works in the finals were "Akhenaten" by Gene Gutche, and Lyric Symphony by Robert Wykes. The orchestra of the Curtis Institute of Philadelphia played superbly in all five of the demanding works. Judges for the competition were Irving Lowens, dean of the Peabody Conservatory; Joan Peyser, editor of the Musical Quarterly; and William Littler, music critic of the Toronto Star.