All over the Washington area, 69 young musicians have been practicing for weeks on Coke bottles, tuned by partially filling them with water. Musical Coke bottles come in two sizes: 8-ounce (treble) and 16-ounce (bass). They are played by blowing across the open top. Each produces one note, so you need quite a few to play a tune. Others (members of a group called Young Strings in Action) are practicing on 11 harmonicas, one in each major key; they are played like harmonicas. The 20 telephone bells, struck with metal mallets, should be manageable, but it is a tricky job producing a musical tone from a water glass.

These instruments, which will be played by 80 members of the audience this afternoon in the Kennedy Center Concert Hall, are a symptom of what is happening to orchestral music at a time when, it seems, anything goes. Our new music is often spectacular. Its flavor can be exotic, but often it produces such effects by putting familiar material (even Coke bottles and telephone bells) in a new light. Above all, it is getting audiences involved, though it seldom has them playing bottles.

Contemporary music comes in many forms and styles. Its deepest underlying forces sometimes seem to be overwhelmingly centrifugal. But there are common tendencies -- trends, if you will -- and today they will be thoroughly sampled at the Kennedy Center. The bottles, glasses and bells will be unveiled, along with a timpani concerto and other more standard material, in the finals of the seventh annual Kennedy Center/Friedheim Awards competition, which is becoming the major national showcase of what is happening in new American music. This year, the subject is orchestral music (in odd-numbered years, it is chamber music) and this afternoon there will be performances of five compositions vying for a $5,000 first prize. In their order of performance: Symphony No. 2, by Edward Applebaum; "Prismatic Variations," by Donald Erb (the one with the bells and bottles); Concerto for Timpani and Orchestra, by William Kraft; "Psalms for David," by Marilyn Shrude; and "The Glass Bead Game," by Claude Baker. Robert Fitzpatrick will conduct the 110-piece Curtis Symphony of the prestigious Curtis Institute of Music in Philadelphia.

One remarkable fact highlighted by the Friedheim competition is the sheer volume of new orchestral music being produced in America. This year's five finalists were chosen from 104 entries that have had their first performances in the last two years.

Such a level of production would not be surprising in chamber music. On purely economic grounds, a string quartet or a piano trio is a lot easier to compose and have performed than an orchestral composition. A few hours of orchestral rehearsal (at a price we can conservatively estimate at $1,000 per hour) can cost more than the commission paid to the composer. There is also the cost of copying the parts for the performers -- again often more than the cost of commissioning the work. And finally, there is the uncomfortable fact that you can always sell more tickets for music by Mozart or Beethoven than by someone named Kraft, Baker or Erb.

The cost-price squeeze works in all directions; old music is cheaper to perform because the players already know it, and it brings in more ticket sales because the audiences already know it.

In such conditions, it is not surprising that modern orchestral music has trouble surviving; it is amazing even that any is being written. The number of new orchestral pieces submitted for the Friedheim competition shows that, at a minimum, American orchestras are performing an average of one new work per week. In spite of the obstacles, there must be more composers producing serious new orchestral music today than ever before.

The canon of orchestral classics is not quite closed. Its center of gravity certainly lies in the 19th century, but new music is slowly being added to the list, against enormous obstacles. Stravinsky's "Rite of Spring" provoked riots 70 years ago; now it is heard in pops programs. Other modern music passing the test of time and ticket sales includes Carl Orff's "Carmina Burana," some of Shostakovich's symphonies and quite a bit of Aaron Copland's work. Will any of the five selections performed at the Kennedy Center today achieve this kind of status? If so, will it be the one that wins the $5,000 first prize, the $1,000 third prize (equal in cash value to the Pulitzer, which still gets more attention) or one of the two honorable-mention awards of $500?

Check back in 40 or 50 years. But at least they are a sign that orchestral music has a continuing vitality, that classical music is not entirely the work of dead foreigners.

The five pieces selected provide a fair cross section of what is happening now in American orchestral music and all are composed at a level of technical skill that speaks well for domestic musical training. All have the "modern" sound; chords that our grandparents would have considered dissonant are taken for granted. But all, in one way or another, show the growing concern of American composers for intense communication with audiences rather than the mere implementation of a structural concept.

The trend toward lyricism and straightforward emotional statement is most apparent, perhaps, in the works of Applebaum and Shrude, though present in all five pieces. William Kraft's work is a technical tour de force -- a timpani concerto is not easy to write, and although he had a distinguished career as a professional timpanist, Kraft doubted at first that he could do it. Erb's variations are a showpiece not only for kids with Coke bottles but for a virtuoso orchestra, with some variations that are changes of color rather than structure.

But Applebaum's symphony is also a virtuoso showpiece -- perhaps because, like Erb's work, it was composed for Leonard Slatkin and the St. Louis Symphony. And Erb's variations are also an emotional statement, as is Kraft's concerto. This music does not fit easily into simple pigeonholes.

Probably the most ambitious work on the program and the one that will sound most "modern" to average members of the audience is Claude Baker's "The Glass Bead Game," inspired by Hermann Hesse's novel of the same name. It is, in a sense, a philosophical discussion of what has been happening in music (and, by extension, in the arts generally) during the last few generations. It is rich in quotes from the work of other musicians, spanning several centuries, and it comments obliquely on musical trends by the way it juxtaposes quotes and references.

Stylistically, it is all over the map, from Baroque styles to atonality and forms based on mathematical concepts. In a sense, it illustrates the plight of the talented and well-trained contemporary composer, who has been handed a vocabulary worked out by centuries of predecessors and is now looking for something to say. Like other works on the program, it is a tour de force and an intense effort to communicate. In a sense, it is a microcosm of the Friedheim competition, which is in turn a microcosm of contemporary American music.