Regina McConnell's soprano has been heard often in recent years in Washington's principal concert halls, and yesterday she gave her second recital at the Phillips Collection. In songs by Quilter and Brahms, Strauss, Berlioz, Barber, and a group of spirituals, she reminded her listeners of the fine basic material of the voice, and of the appealing way in which she communicates with an audience.

There are serious problems, however, that still keep McConnell from attaining the level of excellence for which her voice is well qualified.

Her enunciation, like that of many singers, is simply not clear enough. Even in familiar songs, it was rarely possible to hear most of the words. This was not because the singer was not working at her pronunciation, whatever the language, but because she does not sing in such a way that the words can be understood.

Her voice tends to come out sounding very much the same, whatever the songs, whatever the moods. As the peak phrase of Strauss' "Freundliche Vision," showed, McConnell cannot sustain a soft sound, but depends most of the time on a medium volume. There are many kinds of essential lights and shadows she could apply, but technical problems stand in her way. Gillian Cookson supplied support at the piano that shared the singer's rather bland approach.