THE LATEST word on American music -- word that will be heard resoundingly next Saturday night in the Kennedy Center Concert Hall -- is that it's all right to sound pretty again. If "pretty" is not your favorite word, there are others that you can substitute.

How about "emotional" or "colorful," "accessible," "expressive" or "pleasing to the average listener"? If you want to sound scholarly about it, you could try "quasi-tonal" or "neo-romantic." No one word will describe exactly everything that is happening, but it includes a return of melody to respectable status, a tendency to see music once again as a way to communicate feelings rather than an abstract (even mathematical) structure or a way of experimenting with new sounds.

Whatever vocabulary you choose to describe it, all of the orchestral music to be played Saturday night in the finals of the Kennedy Center/Friedheim Awards sounds a bit old-fashioned -- more like the music of a half-century ago than of 20 years ago. The Friedheim, named for a distinguished pianist, the late Arthur Friedheim, is the only significant competition in existence for new American music.

Its awards, of $5,000, $2,000 and $500, are given to chamber music in odd-numbered years and orchestral music in even-numbered years, and entries are restricted to works that have had a premiere performance in the two years before the competition. The prizes are given after a free concert at the Kennedy Center (6:30 p.m. next Saturday, with Peter Eros conducting the Peabody Conservatory Orchestra).

In order of performance, the five compositions will be: the "Fire Variations" of Dominick Argento, 55, who won the Pulitzer Prize in 1975; the First Symphony ("Age of Victory") by Thomas Ludwig, 30, of Washington; a Guitar Concerto by Ivana Themmen, 42, who is almost the only woman composer to have work performed by a major American orchestra in the last two years; "Avanti!" by 50-year-old Gundaris Pone', who was a semifinalist in last year's Friedheim Awards and won first prize in the international competition in Trieste last year, and "Happy Voices," by 1980 Pulitzer Prize winner David Del Tredici, 45.

No listener who is able to enjoy Stravinsky's "Rite of Spring" should have problems with the musical language of any of these pieces. They all exemplify a return to traditional styles of music that began happening in American composition around the mid-1960s -- a mere trickle at first, but now a phenomenon more like Niagara Falls.

Irving Lowens, one of the founders of the Friedheim competition and its chief juror since its beginning, has examined hundreds of new American compositions in that capacity -- 80 original entries in this year's competition alone. He says that a return to expressiveness, tonality, conservatism or lyricism -- call it what you will -- is "very definitely a trend I have noticed in the five-year history of the competition. Each year, there has been an increase in the number of works that are tonally centered and a corresponding trend away from serial composition. There were some dissonant works and a few minimalist works among the 80 submitted this year -- but almost none in serial forms."

Some people believe that music, like technology, should march ever forward, constantly saying new things in a new language. For them, the five pieces to be played next Saturday night will represent a serious step backward. But to the composers (and perhaps to a majority of the audience) it may seem more like a step aside--out of the path that some enthusiasts of the system of Arnold Schoenberg and its later elaborations have considered the inexorable route of musical progress. The attitude toward the past embodied in most of this new music seems to be one not of return but of acceptance; composers are less interested in going "beyond" what has already been done and more inclined to examine the past with tender care and use its varied techniques for their own purposes.

In a sense, much of the music of the last generation can be seen as a series of vocabulary-building exercises. Composers tried a variety of techniques -- including the use of chance elements and improvisation, electronic sounds, serial organization of rhythm and other structural elements besides pitch, microtones and computerized manipulation of sound -- to see what could be done with them. Some of these experiments became works of art; many were merely "interesting," and all too often the particular artifice being explored seemed to become an end in itself. Composers produced many works which were tours de force -- something like a novel written entirely with words beginning with the letter "A."

Composers of the '80s do not exactly scorn these experiments or their results. Instead, they assimilate them. The important thing now is that more composers have something to say, and the something is likely to be more emotional than cerebral. Their approach to new techniques has advanced from "how does this work?" to "how can I use it?" And what they feel free to use is not only the latest gimmick but whatever works best for a particular purpose -- even tonality.

The chief loser in the new trend seems to be the system of Arnold Schoenberg and his disciples -- serialism, which imposed rigorous, atonal restrictions on the way sequences of notes could be used. Among some ardent devotees, serialism seemed to take on some of the qualities of a religion, demanding total allegiance. Enthusiasts have acted as though composers had a moral obligation to use these techniques -- to keep up with the style of their time -- and those who did not choose to do so have been condemned in terms like those that the Spanish Inquisition once used for heretics.

The ranks of musical heresy have been swelling in recent years, spearheaded by George Rochberg who began as a devout serialist but began to find its expressive resources too limited for his purposes in the 1960s. He is regularly consigned to the musicological nether regions by the theologians of serialism. It may have been some kind of a reply when he gave the heroes romantic melodies and the villains atonal music to sing in his latest opera, "The Confidence Man."

While the existence of a trend has certainly been established, it is too soon (and perhaps it may never be possible) to pin down what is happening with a narrow definition. The five works in the Friedheim finals are similar in their departure from the recent past but quite varied in all other respects.

Argento's "Fire Variations" is intricate music, sometimes violent in its contrasts but reassuringly familiar in its overall form (the theme and variations, which is the oldest form of instrumental music still currently in use) and in its flavor. The original melody is a blacksmith's song from Argento's opera, "Great Expectations," and the composer has made a special point of incorporating "musical gestures . . . suggested by different images and kinds of fire -- smoldering, crackling, comforting, threatening, etc." Argento admits cheerfully that one of his models for the composition was Brahms -- in one of its dimensions, it is a set of variations on the procedures used by Brahms in his Variations on a Theme of Haydn.

Ludwig's "The Age of Victory," written as a response to Leonard Bernstein's "Age of Anxiety," is a stormy, mysterious, dramatic but ultimately optimistic piece. Its techniques are highly eclectic, but its emotional and stylistic center of gravity lies fairly close to the music of Shostakovich and Prokofiev. Ludwig considers himself part of a trend in which composers are "not looking back but taking a different approach." They are no longer trying to be "original in terms of the external aspects of the music, the technique," but rather seeking ways to communicate with the audience.

The Themmen Guitar Concerto follows the traditional three-movement form used for most concertos since the time of Antonio Vivaldi. It is written for a big, colorfully used orchestra, late romantic in its basic flavor except for its large percussion battery. Composer Ivana Themmen says her goals in composing the work were chiefly "displaying the virtuosity of the player and bringing out the beauty of the instrument. The latter is most important to me, as I believe all music must have beauty."

Gundaris Pone', frequently uses the instruction "Avanti!" (the Italian word for "Forward!") in his music "as an exhortation to players to make a particularly flamboyant musical gesture, or to take a recklessly bold chance, or simply to play with extra flair and bravura." His goal is music that is "larger than life" and he says that using this direction as the title for an entire composition "transforms what I first used as a mere exhortation into a set of grand gestures designed to constitute a major statement on esthetic position." Despite some modernistic techniques used in the performance, that position seems to be one of pure, unabashed romanticism.

"Happy Voices," is part of a long cycle David del Tredici is composing under the inspiration of Lewis Carroll's "Alice" books. The title is accurate although (for the first time in this cycle) it includes no singing. At the end, there is a brief part for a wordless woman's voice -- offstage and preferably in an echo chamber; but it is optional and the sound is used instrumentally, not vocally. The "voices" are those of the enormous fugue (exactly 100 pages of 32-staff orchestral score) that constitutes the music. Its underlying subject, in its melodic and rhythmic movement, may remind audiences ever so slightly of Gershwin.

Del Tredici explains the title by the fact that he was asked to compose "some happy music," but the generally accessible style of his work in recent years can be explained by his venture into Carroll's Wonderland. His earlier music, he has said, was "very hard, very hard-edged," but, "I couldn't imagine setting a Carroll text to dissonant music. Dissonant music can't possibly project the mood that surrounds Carroll's writing. In order to create that mood, I had to think about tonality again, not because I was trying to bring back the music of an older period but because I just had to invent things in that language."

It is impossible now to say which of these five works will win the prizes, but one clear winner will be the idea of music as food for the soul.