Joan Armatrading is like olives: A taste must be developed, but once you've acquired that taste, the rewards are exquisite.

Not that Armatrading is initialy inaccessible; her previous albums have always contained strands of commerciality sewn discreetly into her unique sound. Though she's never achieved mass appeal, Armatrading is not working to avoid popular success in the name of art, but to gain it without radically altering her personal creative expression.

"Show Some Emotion" (A&M SP 4663) still may not contain that elusive "hit," but it does contain a talent that demands attention. Armatrading combines influences from her native West Indies and adopted England, and her voice projects both tenderness and power. This is especially true of the title out and "Warm Love" (Armatrading's, not Ven Morrison's), an evocative torch song enhanced by Brian Rogers' tasteful string arrangement.

"Kissin' and a-Huggin'," which she has performed in concert for some time, is as suggestively erotic as modestly allows, and Armatrading proves again that a direct delivery does not necessarily sacrifice subtlety.

All her records have been musically tight and expertly produced, and "Show Some Emotion" is no exception. Despite a reshuffle of most of the touring band in the last year, Jerry Donahue (once with Fairport Convention) is still around to fill in guitar runs and keep the players in line. Glyn Johns, one of the most respected producers in rock, provides resonance throughout the effort and gives Armatrading's solo performance of "Woncha Come on Home" and extra dimension.

If anything has changed stylistically, "Show Some Emotion" has more of a middle-of-the-road sensibility than Armatrading's previous work. But there is certainly no lack of rhythm or energy.

Possibly, unable to attract a larger rock audience, Armatrading will go over their demographic heads with "Warm Love" or "Piece in Mind" to garner the recognition she deserves.

Whatever the commercial outcome, Joan Armatrading is a practicing artist in a field populated more and more by technicians. She takes her cue from her album title and shows some emotion. And more.

Among other recent releases: Chris Hillman, who first combined folk and rock with the Byrds and then country and rock while co-leader (with Gram Parsons) of the Flying Burrito Brothers, is solo for the second time on "Clear Sailin'" (Asylum 7E-1104).

Despite the presence of Poco's Al Garth and Tim Schmit (said to be replacing Randy Meisner in the Eagles), Michael Clarke and Jock Bartley of Firefall (Clarke also being a former Byrd), and Joe Lala of various Steve Stills bands, this is definitely Hillman's album.

Danny O'Keefe's "Quits" highlights side one, which has a distinct country flavor. Side two finds Hillman stretching out into other modes.

Smokey Robinson's "Ain't That Peculiar" is crisp and funky, while the title track is smooth and evocative. Hillman's voice is not particularly strong but it is tuneful, and he has an uncanny sense of harmony honed by his years with the Byrds, Burritos and Manassas. Those who heard him straining for power while he was with John David Souther and Richie Furay may be pleasantly surprised by the vocal ease of all the tracks, up-tempo and ballad.

"Clear Sailin'" deserves attention and Chris Hillman deserves recognition, both as an innovater and as a consistently high quality performer. Whether he achieves stardom or not, it's nice to hear that a talented, laid-back style can still produce top-flight music.