She was born Clementina Dinah Campbell and, a few years ago, Derek Jewell of London's Sunday Times called her "quite simply the best singer in the world." An accomplished actress and near legend in her native England, she made her American debut in 1972 and The New York Times' John S. Wilson immediately claimed that she was one of Britain's "national treasures." Despite all this, she is not a household name. In fact, to many people, she's no name at all.

But Saturday night Washington gets another chance to discover Cleo Laine.

Laine has visited the area many times before, but she's never been able to generate the kind of excitement associated here with, say, Barbra Streisand or Ella Fitzgerald. Unfortunate, since Cleo Laine's voice is just as unique and overpowering as any that ever left a larynx. Laine can dip effortlessly into smoky lows and then reach through the stratosphere for perfectly pitched highs. And she can hold most notes at either end long enough for you to get a cup of coffee.

She's coming to the Kennedy Center Concert Hall to promote her new album, "Gonna Get Through," whose title seems to be a statement of determination to reach the mass audience that has eluded her up till now. The record's contents are further proof that she has made popularity her latest mission.

Besides that incredible voice, Cleo Laine offers an actress' flair for interpretations. She has done opera (George Newsom's "Arena") and musical theater ("Showboat") as well as "straight" dramatic work (Iben's "Hedda Gabler"), so it's not surprising that her concerts are consummate performances.

Songs like "Mad About the Boy" become mini-plays with Laine starring in multiple roles, and Ralph McTell's "Streets of London" - a Laine trademark - is a moving vignette of pointed observation.

What Laine has done on "Gonna Get Through" is concerntrate more on consumer taste than musical suitability. The result is an album that offers familiar songs, but little of the depth that has distinguished most of her other efforts.

Instead of Cole Porter and Stephen Sondheim, "Gonna Get Through" has titles by Billy Joel, Jim Croce and Stephen Bishop, who is quitely becoming one of America's top songwriters; the compositions are contemporary, but not particularly complementary to Laine's intense stylings.

The Leo Sayer hit "When I Need You" is even more schmaltzy here than it was the first time around. Bishop's "On and On" (just about everyone now covers "On and On") is done with an island lilt. This might have been significant since Laine's father is Jamaican (the song opens, "Down in Jamaica / they have lots of pretty women"), but the arrangement is much too cutesy to be effective.

The tunes arranged, at least in part, by her husband, John Dankworth, fare much better. Dankworth, whose band will back his wife's act here, is a legitimate jazz master and sensitive to her talents.

The title cut lets Laine stretch out, and "I Believe You" may be the strongest cut on the record. Dankworth takes some of the blame for "When I Need You," but generally he outshines co-arrangers Ken Gibson and Paul Hart, and he also chips in a nifty sax solo on Joel's "Just the Way You Are." Gibson's triumph is "The Wish," which could jerk tears from a stone.

The album suffers primarily because it's more a concerted effort for radio airplay than a showcase for Cleo Laine's brand of expression. Still, she could probably sing "99 Bottles of Beer on the Wall" and be convincing, so there's no need to mourn for "Gonna Get Through."

While Laine moves from classical and Broadway influences toward the middle of the road, Phoebe Snow gravitates toward the center from rock and jazz roots. Snow, who will be in town Sunday night at the Warner Theater, has just released "Against the Grain," an album with much the same problem as "Gonna Get Through."

Five years ago, songs like "Poetry Man" and "Harpo's Blues" established Snow as a jazz voice to be reckoned with. Since her first album, though, Snow has drifted more and more towards a blander mix.

"Against the Grain" continues the patterns of "It Looks Like Phoebe Snow" and "Never Letting Go," but there are some excursions here that prove she still has unlimited potential for growth.

"Keep a Watch on the Shoreline" and "Random Time" employ unexpected twists that borrow from both rock jazz Jon Faddis bridges "Random Time" with a haunting flugelhorn solo, while Steve Khan's electric twelve-string energizes "Keep a Watch on the Shoreline." Snow's cover of Paul McCarthey's "Every Night" shows that she's not a bad interpreter, but her own compositions are far more interesting.

Since her association with producer Phil Ramone (Paul Simon), Snow has aimed for a broader audience by slicking up her act and playing it safe.

Ironically, that approach has alienated most of her rock fans, disappointed her jazz followers and failed to capture the middle-of-the-road audience that would be most likely to pick up the slack.

Phoebe Snow will be trying out old and new material alike this weekend, and her influences are so diverse, and some of her material so strong, that it's almost inconceivable that her show could be dull.

Snow is only 26, and "Against the Grain" is another step in building a foundation for a lasting musical persona. In contrast, Cleo Laine will be 51 at the end of this month, and her artistic contributions are already accepted. Still, both will present something more than their songs this weekend. Cleo Laine and Phoebe Snow should answer some questions posed by careers in transition.