On A Sunday evening late last March at the Hirshhorn Museum, the 20th Century Consort gave the world premiere of "Sparrows" by Joseph Schwantner.

The name was not a familiar one. Neither was an idea suggested in the program notes, which said, "In recent years Schwantner's compositions have developed a more accessible style, departing from the complex, dissonant textures of his earlier work and evolving into music with ideas much easier to grasp on first hearing. As the composer puts it, 'What is on the surface is more easily perceived.'"

"To grasp on first hearing"! That is not what composers have been saying for the last 20 years or so, at least until very recently. And how could "what is on the surface" possibly be sufficiently complex to satisfy those who demand that the newest also be the most inaccessible? Yest a few short weeks after those words appeared at that premiere, Joseph Schwantner, 36, received the Pulitzer Prize in Music for 1979.

He was in town recently, in company with the Eastman Philharmonia, which played the work that brought Schwantner his Pulitzer: "Aftertones of Infinity." I asked him if he would like to expand on that idea of public enjoyment the first time around.

"Yes," he replied eagerly. "Any composer would hope for that. I have been making a conscious effort to simplify the techniques." The next question was essential: Did Schwantner see his change of compositional direction as a part of a trend?

His answer went straight to both his own training at Northwestern University and to his present occupation as an associate professor of composition at the Eastman School of Music. "I am a product of the universities at the time when composition students were told they had to justify their existence by writing something that was new.

There -- not to oversimplify the situation -- is a key to what is happening in the writing of music as we prepare to enter the 1980s. The change is very decidedly a marked alteration from a pattern that began long before the '70s.

In the largest sense, it is a moving-away from the dead ends to which many composers were led with the coming of what is commonly called atonality or 12-tone or serial techniques. They in turn led to experiments in which, to the general public (and often to the trained musician as well), it seemed as if any semblance of recognizable melody, harmony and rhythm had been abandoned. Those who followed the 12-tone principles laid down by Arnold Schoenberg found, in many instances, that his system had built-in mechanisms that applied to rhythm as well as to melody and harmony.

In striving to (or worse, being instructed to) "find something new" at any cost, many younger composers turned out music that was usually correctly described as sere, arid, academic, tedious -- or, bluntly, barren of any interest.

Faced with what seemed to them blind alleys, some composers began to experiment with music of chance, which was immediately labeled by the snobs "aleatoric," or "stochastic," depending upon your preference for words of Latin or Greek derivation. Lukas Foss, one of the foremost explorers of this new region, once told me why he stopped writing music of chance -- in which the performer or performers are left to their own devices to make up, or improvise, from the composer's beginnings; or to choose for themselves from either finite or infinite numbers of possibilities in performance, by picking the notes, or durations of notes, or entire sections of works they wished to use, or to ignore.

"After a while I stopped writing music of chance," Foss said, "because I realized that when I did that, I was becoming a noncomposer -- and I am a composer." Soon after that, however, Foss, who is best known in this idiom for his Time Cycle and Baroque Variations returned to it like a prospector who is not sure he has mined all the precious metal from an earlier strike.

Concerts in the lat '50s and '60s frequently reached nadirs in programs where -- before a group of perhaps 40 or 50 obviously dedicated believers -- players of violin, viola and cello would carefully move their bows back and forth above the strings without making a sound. Or, perhaps, once or twice in a 15-minute work, they would permit a single pregnant note gingerly to be heard.

Or, in those same compositions, a clarinet player might hold his instrument an inch or so from his lips and gently blow near, across or (from a safe distance) actually into it -- but, like his string colleagues, without making a single sound. Now and then, he might once or twice actually produce a low, soft sound somewhat like a signal horn on the now-forgotten Liberte, as she sailed out through the Narrows on a foggy day.

If some people were hornswoggled by these pseudointellectual hoaxes, the general public, with its thousands of intelligent music lovers, was not. While certain compositions such as Alberto Ginastera's great opera, "Bomarzo," have employed music of chance as one technique among many, no single work in this idiom has ever established itself in any repertoire.

Much the same must be said of electronic music in spite of hundreds of works that today regularly use electronically produced sounds as part of their total music fabric. Like every valuable compositional resource, both 12-tone music and electronic music have been absorbed into the complete reservoir from which the most imaginative composer selects those materials he wants to use.

What Schwantner is talking about when he hopes that the public might enjoy his music at a first hearing is not oversimplification either in technique or style but a desire, and one that was as well known to Monteverdi as to Mozart, to Verdi as to Wagner, that the large listening audience would love their music and want to hear it again -- soon.

Some of Schwantner's most world-famous older colleagues have made similar alterations in their styles in recent years, and like him, have talked about them.

A year ago, just before the world premiere of his large-scale opera, "Paradise Lost," in Chicago, Krzysztof Penderecki told a large gathering of music writers, "My music is 90 percent different from what it was nine years ago." You can hardly be more specific than that. Nine years before was Penderecki's reference to the time when he wrote his first grand opera, "The Devils of Loudun."

Among the differences in the two works, it was easy to hear the steady progress toward clearly defined tonalities in "Paradise Lost," which consistently offered large episodes that were solidly and recognizably grounded in such familiar territories as B-flat, E-flat and C-Major. And the choral writing had textures that differed mightily from those of Penderecki's earlier "Utrenja," differences that could not be explained away by any simple difference in text or purpose.

Albert Ginastera, now 63, talked about the same phenomenon last year when he was in Washington for the premiere of "Glosses," and the final version of his Cello Concerto.

Asked if he saw a general return to a more "romantic" style of writing, Ginastera answered, "I would say, rather , that I am using a more lyrical approach."

Today Joseph Schwantner is teaching composition. Obviously he is not going to make those mistakes -- for that is what hindsight shows them clearly to be -- that his teachers made when they insisted on something new at whatever cost. He is telling his students that if they hope to find listeners who want to hear their music and hear it again, they must not be afraid to write music that has immediate attractions.

All this makes Leonard Bernstein, writing in 1966, sound like a prophet ahead of his time. He wrote in his book, "The Infinite Variety of Music": a

"It can be no more coincidence that after a half a century of radical experiment the best and best-loved works in atonal or 12-tone or serial idioms are those works which seem to have preserved, against all odds, some backdrop of tonality -- those works which are richest in tonal implications."

It is not only the end of the '70s that is approaching. It is the end of of two decades in which "new music" often became two of the most objectionable words in any language to many people who truly and persistently loved music. It was a time without precedent in the history of music. It is over.