''I can't keep up with myself,'' Morton Gould complains cheerfully, as he reaches age 70 and new acclaim. Just back from the world premiere of one of his works in Arizona, the composer, conductor, arranger, and pianist now surveys his tails and prepares to attend another first performance - this one of his ''American Sing'' opening for the Olympic Games by the Los Angeles Philharmonic and the four renowned singers Placido Domingo, Benita Valente, Florence Quivar, and Paul Plishka.
We're standing in Gould's Tudor-style house in Great Neck, Long Island, and soon climb to the top-floor, giant studio where he works. Five feet, 9, slender, with perceptive blue-gray eyes, he looks much like a pixie and acts like age 24 or 25. He wears brown slacks, a tan shirt without tie, a touch of mischief overall. Father of four, grandfather to four more, he's modest and implacably amusing. A gentle man, also a mensch, he must measure 8.9 on the Richter scale of males. He won the prestigious Golden Baton Award last year, and he serves on the American Symphony Orchestra League board, as well as the board of ASCAP, where he chairs the Symphony Concert Committee.
''That's why I never have time for anything,'' he says with a smile. ''I don't even have time to deteriorate.''
Considered one of the top nine or 10 living American composers (with Copland, Bernstein, Schuman, Carter, et al.), he generally manages to combine quality with commerciality, a knotty task for most. Further, Gould is much more versatile than most, able to create six symphonies, symphonettes, chamber music, ballets, choral works, Broadway shows, movie, and TV scores. Included among this work are ''Spirituals for Orchestra,'' ''Interplay,'' ''Fall River Legend,'' and scores for ''Billion Dollar Baby'' with Comden and Green and for the TV series ''World War I.'' As conductor, he has led orchestras around the world and made first recordings of important works by Shostakovich, Ives, and Copland.
That same Copland, dean of American composers, told me: ''Morton is one of the main composers of American music today. He's also one of our most played composers. He's covered a wide range, from classical to popular, and I think that's one of the most important things he's been able to do. He's unique, with perhaps Bernstein, in being that varied and all-around.''
Next season - 1984-85 - Gould unwraps a major effort, a flute concerto for the esteemed Chicago Symphony and first flutist Donald Peck, conducted by Sir Georg Solti, followed by other new pieces for the Pittsburgh Symphony and Andre Previn, and then for the Atlanta Symphony and Robert Shaw. Fortunately, he can work while traveling, on planes and in hotel rooms, since he composes in his head, not at a piano: a convenience, he says.
New York-born, of Russian-Austrian Jewish extraction, he began as a child prodigy - first published at age 6 - and has created more than 1,000 pieces since. As for judging his own output, he doesn't. ''Once I've done with any work of mine, that's it. The great charge is in the doing. All the other things are wonderful - the opening, etc. - but the big thing for a creator is the act of creating.''
While Gould doesn't judge his work, others do. One negative persists, and it comes generally from people who don't know his weightier fare: He's not serious, not a highbrow; he just writes pops and light classics. The Pulitzer Prize-winning classical composer William Schuman (among others) objects to this criticism. ''I have a profound disagreement with anyone who says he's not serious,'' Schuman declares. ''He's a commercial composer, but he also writes serious art music. The 'Jekyll and Hyde Variations,' for example, is quite remarkable and not commercial. He suffers, in evaluation, because he's ambidextrous, but he's a very serious artist. His exact opposite is probably Elliott Carter, who's complicated and dense on purpose, whereas Gould is clear and says what he wants to say with an economy of means. People confuse complexity with worth.
''Gould hasn't attracted accolades from the scholarly community, because these intellectuals like to describe music and write convoluted program notes, whereas Morton's music is in that wonderful category that's better listened to than talked about. That's the highest praise I can give any music. He's underrated and underappreciated,'' Schuman asserts.
''Composer Phillip Ramey runs up the scale of outspokenness to say: ''Morton has great craft and good taste, but of course he doesn't aim for the same things Beethoven did. I wonder if that's less good than a 'serious' composer like Elliott Carter who writes music that aims high, but is expressionless. I'd rather hear a Gould piece than a Carter piece any day, because one is musical and the other is not.''
Certain critics hammer at a second negative, that Gould has marvelous technique and form but inferior content. Thus some of his music becomes forgettable, speeding ''in one ear and out the other,'' according to New York magazine's Peter G. Davis. On history's anvil, this blow seems true - of Gould and also of others.
Sitting now at the large drafting table in his studio, Gould observes that he and Copland, et al., are the first generation of American composers able to be compared favorably, in stature, with European composers. ''We're the first real school of American composers; we've all worked with American music idioms like jazz and folk songs. It couldn't have happened sooner, because we were dominated musically by Europe, the Germans especially, and we had to develop our own personality. There were individuals before, however - Charles Ives, a giant figure.'' His own purpose, he says, is to be accessible to his audience. One should get a general sense, though probably not get everything, on first hearing.
The maestro smiles through the window at his maple trees and goes on: ''I don't agree with those who feel that the latter half of this century is relatively poor in important, serious music. This country is overrun with rich, creative efforts, with all kinds of schools from the most complicated to the simplest. But music is not to be explained. Either it has an invention, a fantasy, and a creative face to it or it doesn't. Everything else - a lot of talk and theorizing - is hogwash. A piece can be Minimal music or Maximal, but these are just words. Is there a 'Maximal'? I don't know, I expect one any day.''
To some, Gould's scores get better and better. Charles Wadsworth, artistic director of the Chamber Music Society of Lincoln Center and an accomplished pianist, commissioned the 1982 ''Suite for Cello and Piano'' and discovered that , ''nearing age 70, Morton was continuing to grow and develop in a very fresh way. Often composers, when they hit their 40s and 50s, start to dry up and just produce carbon copies of their past work.'' Mr. Wadsworth continues: ''This came out a very strong, important piece, combining all his best qualities and adding a few I'd never heard in his work before. The first movement has a tremendous, granitelike strength, and its textures are almost Brahmsian. There's much more intensity, caused by the dissonances he uses, than one normally associates with him. The New York Times ran a terrific review - '... warm and darkly Romantic music' - and most new pieces these days don't get good reviews.''
Serious as he is, Gould can be equally humorous. Herewith some bons mots - though actually they're meilleurs mots:
After a recent rehearsal, a trumpet player complained jovially that Gould had written no part for him. Gould: ''Why don't you just play along, anyway?''
Regarding a Broadway composer of great conceit: ''He compared himself, talking with you, to Beethoven. Even Beethoven never compared himself to Beethoven.''
''How did my Detroit concert go? All right. I did a concert there. It's gone. Detroit hasn't improved.''
Finally, in answer to the classic Hollywood reporter's query (posed by me as a joke), ''Do you sleep in the nude?'' Gould says, ''No, I sleep fully clothed. Generally in tails - so that I'm ready to go.''