SUDDENLY, we are surrounded by chamber orchestras and its about time. The trend began 30-odd years ago, shortly after the development of long-playing records, when previously unknown organizations with names like I Musici and I Solisti di Zagreb began to make noises on our loudspeakers.

Now they are with us in person. Both of those groups have visited Washington in recent seasons, as well as others from all over Europe and America. The Y Chamber Orchestra will come down from 92nd Street in New York City May 2 to make its Washington debut, and it will be followed May 10 by another New York chamber orchestra, Orpheus, whose 26 members perform without the benefit of a conductor. In June, it will be the St. Paul Chamber Orchestra with violinist-conductor Pinchas Zukerman, and in July the Mostly Mozart Orchestra, which exists only in the summer when its members are not too busy with other assignments. Not that we need to import them; Washington has at least a dozen chamber orchestras of its own.

The rebirth of the chamber orchestra means that our musical tastes are changing, expanding. We are not abandoning the big symphony orchestras and philharmonics, but we are looking for a wider choice of music. For a century, more or less, orchestral music meant music by big orchestras--an overwhelming experience for those who want to be over- whelmed. But there are other values in orchestral music: intimacy, light textures, the feeling that you are dealing with individuals rather than an army.

Big orchestras are a 19th-century phenomenon; they reflect the spirit of the Industrial Revolution and an age of empire-building. For a generation that has accepted the slogan "small is beautiful," other kinds of music should be available.

How about oboe concertos, for example? In the century of Bach, Handel and Mozart, they were written by the dozens, as were concertos for the lute, the guitar, the flute, the clarinet and even the lowly bassoon--shy, delicate, retiring instruments that make beautiful sounds but not loud ones. Look for this kind of concerto in the 19th century, and you draw almost a complete blank. Composers at that time wanted to bare their tender souls, which could be done most easily in a violin concerto, or to throw massive temper tantrums, for which a piano was most useful. The beauties of abstract design, the function of music as entertainment were largely forgotten in the process.

The 19th century added something to the intensity of music, but it reduced the number of available colors--at least at the pastel end of the scale. Guitar concertos, flute concertos, oboe and bassoon concertos are being written again in our time. Some of them are for standard orchestras--though the composer must make these leviathans tread lightly to avoid crushing the fragile soloist. But usually they are best heard with a chamber orchestra, and they reflect the sensibility that has revived chamber orchestras.

IN 1978, representatives of chamber orchestras in the United States and Canada held a meeting under the auspices of the American Symphony Orchestra League. At that time, there were more than 150 of them, and the number has undoubtedly grown since then, though nobody is counting. One useful by-product of that meeting was that it produced a generally acceptable definition of a chamber orchestra: "an instrumental ensemble of not less than 12 strings or more than 40 players in all" that "performs repertoire either explicitly composed for chamber orchestras or intended to be performed by more than one player per string part." That definition includes practically every piece of orchestral music composed before 1800, a substantial amount of music composed since World War I and precious little in between--mostly serenades by Dvorak, Brahms and Tchaikovsky.

One reason for the blossoming of chamber orchestras is economic: 12 to 40 players cost less than 100 to feed and transport on tours, to pay for rehearsals and concerts. But there are more important esthetic reasons.

Orchestras began to grow larger at about the same time that pianos and violins started to become louder, in the 19th century. The process reflected sweeping social changes. During the life of Beethoven (who died in 1827), orchestral music stopped being the almost exclusive plaything of the nobility (who were too busy worrying about the French Revolution) and began finding its support among the general public. As the audiences grew, so did the size of the auditoriums and the orchestras.

At the same time, the visions of composers began to be more grandiose. The process can already be seen in a comparison of Beethoven's First and Ninth symphonies. Obviously, a revolution happened between these two works. The composer had stopped being a member of the servant class--working in a castle, wearing livery and living with the other house servants. He had become a prophet who climbs to the top of a mountain and proclaims a message for all humanity. The revolution's growth, within a decade of Beethoven's death, can be seen in the Requiem of Berlioz, with its massive choral forces, its enormous musical gestures, its four brass bands used to symbolize the angels' trumpets announcing the end of the world from the four corners of the earth.

A lineal descendant of the Berlioz Requiem is Mahler's Eighth Symphony, which dates from 1906 and is nicknamed the "Symphony of a Thousand" because of the massive choral and orchestral forces it requires. But by then, the tide was turning; 1906 was also the year of Arnold Scho nberg's Chamber Symphony for 15 instruments--only five years after he had finished the massive "Gurrelieder," which can keep hundreds of musicians busy for hours on end.

The composer who embodies the final stage of grandiose imagination is Alexander Scriabin, who dreamed of a work called "Mystery" as his final composition. It would be performed in conjunction with the end of the world, possibly on a mountaintop in India or Tibet, and at the climax the composer himself would die in a "suffocation of ecstasy." Instead, he died in 1915 of septicemia.

Igor Stravinsky is a key figure in the counterrevolution of the chamber orchestra, and World War I was the pivotal point. In 1913, he produced "The Rite of Spring," for an enormous orchestra. In 1918, his major work was "L'Histoire du Soldat," which requires only seven instrumental players plus a few actors and dancers.

The reasons Stravinsky began thinking small were largely economic, but they also relate to the neoclassical trend in which he was a leader. Later, he produced many works that are specifically for chamber orchestras or can be very satisfactorily performed by them, including the ballet "Apollo," the "Pulcinella" ballet and suite, the Danses Concertantes and the opera, "The Rake's Progress." One of the landmarks is the "Dumbarton Oaks" Concerto, given its world premiere at the Washington library and research center.

In the late 1700s, when chamber orchestras were allied with the aristocracy, their future probably looked secure. Today, the customers wear jeans and T-shirts and the music happens not in castles but in concert halls, churches, museums, libraries and school auditoriums.

This time around, the chamber orchestra seems headed in the right direction.