No doubt there was a time when part of the pleasure of attending a Charles Aznavour concert was to be found in watching him slowly woo his audience. But these days the seduction is swift--and sweet.

From the moment the diminutive French singer tucked his hands in his pockets and strolled on stage at the Kennedy Center last night, taking his place in front of a small group of musicians, the audience was his for the asking. He spent the rest of the evening effortlessly living up to its expectations.

Possessed of an unspectacular voice and range, Aznavour long ago mastered the art of transforming vocal liabilities into assets. He still sings of love as few others can, imbuing his songs with great charm, intimacy and drama, acting some of them out with the gentle finesse of a mime.

Most of these songs--written by Aznavour and sung in either French or English--shared certain qualities. They often moved from quiet, reflective passages to stirring romantic climaxes savored by singer and audience alike. Replacing Aznavour's sextet with an orchestra certainly would have added punch to many of the arrangements, but the singer's interpretive skills were never in doubt, and he left the Concert Hall just as he entered it--triumphantly.