Leonard Slatkin, soon to become music director of the Saint Louis Symphony, made his National Symphony debut last night in the Kennedy Center.

In placing Donald Erb's Autumn-music first on his program, Slatkin chose no easy path to his audience's affections. However, in his excellent talk, explaining the music, he won himself deserved applause which built, at the end of the work, to shouts of "Bravo!" from some in the hall, while others had simply walked out to avoid a kind of music they did not care to hear.

It is by no means an unfamiliar kind of music in today's concert halls. There is some Ligeti stasis, some highly ingenious use of electronic music's standard patterns, and some extremely unusual usage regular orchestral instruments. Like having the wind players use only the mouthpieces, and the strings play non-pizzicato, but with the fingers alone on the strings.

As always the final question must be: What musical end is served? In this case the final result is not especially impressive except for Erb's skilled mixing of electronic and orchestral sounds.

To some, Ruggiero Ricci playing the second Paganini Volin Concerto fell, after Erb, like balm. The playing, marking the soloist's 50th anniversary before the public, had lyrical song in the slow movement. But the fireworks in the outer movements were often plauged by faulty intonation.

Slatkin was impressive in the First Symphony of Sibelius in the skillful manner with which he held together the highly episodic score. The orchestral sound was not always in the best balance.