Joni, you never fail to surprise.

Your truest fans, including this one, have traveled with you through an amazing range of expressions. We've seen you leap from the barefoot romance of "Blue" to the harsh political playlets of "Dog Eat Dog," and we've shared your musical shifts from jazz and African rhythms to Thomas Dolby's high-tech sonic adventures in the 1980s. Few singer-songwriters have grown into maturity with as much unpredictability and experimentation as you.

And with as much diva free spirit. Condemning your imitators for their "girlie guile " and aligning yourself with Vincent Van Gogh, you have kept us dazzled with an unwillingness to play by the rules of fame. No self-editing, no false modesty, no audience pandering. When listeners wanted you in Birkenstocks, you wore heels; when we wanted more "Court and Spark" sweetness, you gave us the social raillery of "The Hissing of Summer Lawns." You've been stubbornly loyal to your muse, and we've always benefited.

Until now, that is.

Today, Joni Mitchell is releasing a new CD that many of her fans - definitely this one - will not want to play. Called "Travelogue," it is a reinterpretation of Mitchell by Mitchell, with Joni singing 22 of her previously released songs accompanied by a 70-piece orchestra, a choir, and notables such as Herbie Hancock and Wayne Shorter. An extension of the self-reimagining that began on 2000's orchestrated "Both Sides Now," it's Joni somewhere between Broadway and Bach. It's theatrical, it's grandiose, and it's not the Joni Mitchell I want to hear unless I'm looking for distraction in a dentist's waiting room.

Lest you think that "Travelogue" is Mitchell Muzak, let me say that for what it is, it's quality. As always, Mitchell's production (with ex-husband Larry Klein) is meticulous. Each song is arranged to recall but not mimic the original, with formerly dominant riffs reduced to substatements on songs such as "Refuge of the Roads." Her voice is gracefully mixed in with the violins, bassoon, trumpets, and drums, and yet it remains clearly upfront. And her voice is as good as it has been in years - without the multioctave trilling that once distinguished it, of course, but with enough nuance to make her lyrics count. Her tones now have a husky warmth that, ironically enough, may partly result from decades of smoking. On the more successful songs, such as "The Dawntreader," her voice is gorgeously intimate.

And I don't think Mitchell is remaking old material simply to get a new album into stores. There isn't cynicism behind these remakes so much as weariness. I hate to say it, but part of Mitchell's motivation in making "Travelogue" may be a lack of inspiration for writing new songs. Her painting continues to take her in new directions, and she may not have much more to say in words. By redoing old pieces, she may be trying to create a sort of epilogue to her songwriting years, a summarizing career statement.

But Mitchell may be too smitten with the notion that her songs are more durable than we ever knew, that they can flourish in any musical setting. She has proven the versatility of some of her pieces before, when she reshaped material for live performances on albums such as "Miles of Aisles" or on her excellent video "Painting With Words and Music." And her 2000 version of the simple, anthemic song "Both Sides Now" grew into a sunset reassessment of love and life thanks to a sedate orchestration.

But the complicated songs that predominate "Travelogue," such as "Judgement of the Moon and Stars (Ludwig's Tune)," "The Sire of Sorrow (Job's Sad Song)," and "Slouching Toward Bethlehem," don't take on new shadings so much as they lose old ones. Mitchell's fierce intellectualism - what has made her music so superior to her imitators' - is sold short in a swelled-up musical setting where the instruments sound as though they could be cuing choreographed dance moves. Musings on fame such as "For the Roses" or "Troubled Child" are sadly diminished, and "Sex Kills," one of Mitchell's darkest observations about pollution, commercialism, and moral sickness, is rendered almost silly. And occasionally the arrangements force her into awkward enunciations, such as on "Amelia."

Throughout her career, Mitchell has reached toward orchestration in interludes on songs such as "Down to You." But those bursts of thunder came at significant moments, not so consistently that they blurred together. On "Travelogue," all the careful orchestration ultimately prettifies a collection of brilliant songs, songs that frequently call for bite - even if their author has mellowed.

Matthew Gilbert can be reached at gilbert@globe.com.