The Inter-American Music Festival closed yesterday with its youngest participants sounding a bright and beautiful note for the future of music in the Americas. The Arcos y Voces Juveniles de Caracas made its Washington debut with this OAS concert. There was an overflow crowd at the Hall of the Americas, where the doors and windows wereleft open and the songs of these young Venezuelans mingled with those of the birds of spring outside. It was an even match.

The group in 1949 was formed as part of a unique musical kindergarten. It now includes the upper grades, but most of its musicians are not yet in their teens. The orchestra is a fine student group whose exuberance more than compensates for its musical flaws, such as intonation of the upper strings. The choir is brilliant, the kind of group to whom Palestrina and Monteverdi can be entrusted.

Not surprisingly, the unaccompanied singing proved the most delightful. "Alma Llanera" by Pedro Gutie'rrez is perhaps the best-known Venezuelan song, a captivating paean to that country's land, sun and breeze. It was given a stirring interpretation and with the nostalgic "Sendas de la tarde" by Juan Bautista Plaza it was a living textbook of choral virtues.

The group's texture was rich, particularly in the treble section. Its agility and accuracy in fast runs was as dazzling as its intonation was faultless. The clear vocal attacks were especially felicitous in this hall, where the cavernous acoustics tend to distort fundamentals while the rest of the sound suffers a long and dry reverberation. In "Sendas de la tarde" the melodic flow began midstream and the voices toyed with its firm tonal base in a wise and wonderful manner that would escape many older musicians.

The orchestra began and closed with exuberant readings of Mozart. Under the direction of Daniel Bernard, the joy of music was audible . And its future looked promising indeed.