When Joan Amatrading was 14 years old, she saw Marianne Faithful on television and no longer wanted to become a lawyer. On the other side of the Atlantic, Carly Simon was listening, too. So both youngsters took up the guitar and learned to be singer-songwriters, sharing thier innermost feelings with anyone who bothered to listen. In their strikingly different ways, both women -- who have been known for offstage shyness -- were effective in getting more than an emotional message across. The music itself was mellow and comtemplative.

But these tough-talking days, even Marianne Faithful is singing with a raunchy New Wave band. And the recent releases from Simon and Armatrading are, according to trend, much harder than past efforts. Only one, however, manages to pull off the switch.

Though Carly Simon's sound normally veers from folk to jazz to rock on occasion, she has never lost her sense for the commercial jugular. Sometimes "commercial" can be taken literally -- more than one of her tunes has provided a strategy and theme song for a corporate propaganda campaign. On "Come Upstairs" (Warner BSK 3445) she has followed Linda Ronstadt's lead in integrating some New Wave energy into her sound: The studio men here rock out with the freshness of the "cleaner" Wavers like The Cars. But in keeping with Simon's upscale life style, the rock is refined, a high-tech glossy form of electronic precision that never gets sloppy. At no time do we yearn for an "old" Carly Simon -- she's too active here to look back, giving us some bold treatments of mature love (the title tune is an unabashedly sexy song extolling long-term marriage), an unsuccessful stab a Devo-style computer-music, and a set-piece called "In Pain" that embodies every excess she has never dreamed of. "The Letter" is a lengthy screamer that begins in the land of Laura Nyro, moves to the land of Patti Smith, and makes you wish Simon had stayed home in Martha's Vineyard.

Two songs, though, prove that Carly Simon is capable of turning out a thrilling pop song no matter what the current vogue. First is "Jesse," an anthem to feminine vulnerability with an undeniably charming hook. Then there is "Take Me as I Am," a bouncing, piano-driven radio song that restates "the grass is greener . . ." proverb with the literate kind of lyric that makes us wonder why she doesn't do such songs more often. Both songs will undoubtedly appear on Simon's "Greatest Hits Volume II," which we can expect after four more albums -- figuring she turns out only two sizzlers like this each time around.

Unlike Carly Simon, Joan Armatrading has won her fame the hard way, bucking the commercial trends with her own style of music: a quirky, off-sync form of song-crafting that eschews strong melody and relies on her marveleously malleable voice. Her lyrics mark her as a woman who feels deeply, loves hard and maintains a sense of irony. The more your hear her, the more mysterious she becomes -- her albums, at least until "Me Myself I" (A&M SP 4809), arouse intrigue and bear more extended scrutiny than the ditties of her more conventional counterparts.

The hard-rock bug has bitten her, too. Not a New Wave irreverence, but an ear-thumping din that is stupefyingly unsuited to her unique style. Maybe we can blame this on her new producer, Richard Gottehrer, who has done less damage with Blondie and Robert Gordon. In any case, the paradigm of "Me Myself I" is the drumming of Anton Fig, who pounds his skins so hard you can picture him in a sweat-stained tank top, drumsticks lifted high over his head. When you consider that Joan Armatrading's wicked 12-string guitar is usually percussion enough, you can appreciate the extent of the problem. Of the 10 cuts -- strong songs lyrically and structurally -- only one prevails over its arrangement, and perhaps two or three fight the music to a draw.

The sole winner is "All The Way From America." Not coincidentally, it's the only song with Armatrading's guitar prominently featured. Her throaty voice is allowed some room, and you have to melt a bit when you hear the plaintive phrasing she lends to the four syllables of "America."

Normally when a singer records a below-par album, the recommendation is for fans only. But Armatrading's followers are the ones likely to be offended here. Those unfamiliar with her work might enjoy "Me Myself I" quite a lot -- until they discover her earlier albums. Then, like the rest of us, they'll hope that this new one is only a temporary setback for one of the best singer-songwriters we have.