**1/2 Linda Ronstadt & Emmylou Harris

WESTERN WALL: THE TUCSON SESSIONS

(Asylum)

There's a yin-and-yang spirit at work when Linda Ronstadt and Emmylou Harris collaborate. The pop superstar is a stylistic chameleon who formalizes every note she sings. The country-rock chanteuse appreciates a more colloquial vibe; even her most explicitly produced discs can't hide those DC folk roots.

Western Wall is an explicitly produced disc that zigs toward the casual and zags through stuffiness, trying to make sense of this relationship. With Glyn Johns behind the boards, the pair come up with 13 glistening tracks of various weight and worth. In the end, vocal calibration determines value. When Ronstadt wails over a bedrock of guitars on Patty Griffin's "Falling Down," she sells us a big-voweled mantra. When she bellows Jackson Browne's dead-girl lyrics on "For a Dancer," there ain't a clue in site.

Harris fares better. Those David Olney story songs she's fond of allow for nuanced drama -- "1917" is a nice break from her signature twangsicles. And "All I Left Behind" supports its weepy tone with the evocative whisper she's perfected. Ultimately, the record's about harmony: the accord they achieve on both "Sisters of Mercy" and Roseanne Cash's shimmering title cut illustrate why the pair's coalition is manna to their devotees.

-- Jim Macnie