There's fascinating tension in the new records by pop singers Phoebe Snow and Deniece Williams. The voices of these two women represent powerful, persistent emotional impulses. Those impulses are roped in and weighed down by the easy-listening sentiments of their producers.

Snow has a jazz-trained voice that can leap octaves effortessly in search of a personal touch. On "Rock Away," these gymnastics are burdened by the commercial baggage of producers Greg Ladanyi (Jackson Browne's engineer) and Richie Cannata (Billy Joel's saxophonist).

These producers saddle Snow with the kind of pop-rock that plods along without disruption or challenge. Fortunately, Snow is able to escape their restraints to create some special moments on the album.

Deniece Williams has a gospel-trained voice that soars into ecstatic shudders when overcome by emotion. On "My Melody," her hot emotions are cooled by the calm and commercial instincts of producer Thom Bell (architect of the Philadelphia soul sound).

Bell wraps Williams' distinctly personal voice with soothingly anonymous voices and strings. Though Williams breaks through this gauze for a few special moments, she generally has less luck than Snow.

By contrast, there is almost no tension on Debra Laws' "Very Special." Laws has a pretty but impersonal voice that sounds comfortably at home with the faceless, pop-soul arrangements of her producer/brothers, saxophonist Ronnie Laws and flutist Hubert Laws.

Billy Joel's backup band appears on eight of the 10 songs on Snow's "Rock Away" (Mirage WTG 19297). They're competent Hollywood studio musicians, but they lack the flexibility of Snow's three-octave range. The band often marches steadily on while Snow's voice twists and turns like a tethered falcon above them.

On Rod Stewart's "Gasoline Alley" and Allen Toussaint's "Shoo Rah, Shoo Rah," Snow and Joel's band march right up to the brink, but refuse to jump off. One gets the feeling that Snow would like to, but the band's adamant refusal to change tempo holds her back.

Snow wrote three songs for the album. The best is the title tune, the only song featuring Snow on guitar. This sparse acoustic song achieves a genuine pastoral feel. Significantly, it's the only understand song on the record.

The only musician who is up to Snow's vocal demands is former Little Feat keyboardist, Bill Payne. Payne's unsettling synthesizer eggs on Snow's wailing voice till "Games" becomes quite threatening.

Payne's swelling organ chords underline Snow's confident vocal on Bob Dylan's born-again gospel hymn, "I Believe In You." The sneering arrogance of Dylan's version is replaced by Snow's calm assurance.

Snow's entire career has been haunted by the brilliance of her 1974 debut album, "Phoebe Snow" (Shelter SR 2109), which she hasn't yet matched. That album features intoxicatingly convoluted lyrics and virtuoso playing by Zoot Simes and David Bromberg. It's difficult listening but well worth the trouble.

The long shadow of Snow's past has caught up to her again with the release of "The Best of Phoebe Snow" (Columbia FC 37091). This contains the two high points of her Shelter debut plus eight songs from her four Columbia albums.

Deniece Williams' sound changes with each new producer Maurice White (of Earth, Wind & Fire) surrounded her with horn-dominated pop-soul on the 1977 "Song Bird." Ray Parker (of Raydio) surrounded her with guitar-dominated pop-soul on the 1979 "When Love Comes Calling."

Now Thom Bell has surrounded her with the harmony vocals of Philadelphia soul on "My Melody" (ARC/Columbia FC 37048). Bell and two other men huff and puff out harmonies like the old Spinners.

Williams and Bell together wrote six of the record's eight songs; Williams collaborated with Fritz Baskett and Clarence McDonald on the other two. The songwriting is the album's weakest link. "Life's music can make you want to cry" is typical of the hackneyed cliches. The melodies are bland, short phrases repeated over and over.

It's Williams' grand voice that salvages some splendid moments on the album: When she breaks loose from the songs' blueprints and starts to improvise the music finally comes alive.

"Strangers" gets three mintues of standard interpretation, but then breaks into three more minutes of delightful vocal improvisation. Repeating a few simple words over and over, Williams' voice cuts phrases in half with shuddering squeals and husky asides. She captures the sense of a calmy planned confession undone by a Pandora's box of emotions.

"Very Special" (Elektra 6E-300) is Debra Laws' debut album, though she has sung on her brothers' albums. They returned the favor by producing "Very Special." The Houston family also boasts recording artist Eloise Laws, who sings harmonies on one song.

Unfortunately, only Hubert Laws has displayed any special talent so far, and he has been content to obscure that talent in pop-jazz formulas. If Debra Laws has any particular talents, they are well-buried in the pop-jazz formulas that suffocate this album.

Debra Laws sings pleasantly enough, but she could have been replaced by any of special dozen Hollywood studio singers with no difference. The studio veterans, such as keyboardist Larry Dunn of Earth, Wind & Fire, and the Laws brothers, sound as if they've played the same riffs a thousands times before. They have.