Joni Mitchell doesn't mean to be so melancholy.

"I just can't help myself," says the quintessential singer-songwriter, with a giggle. "My music forces me to be a tragedian."

That's right, a giggle. Mitchell may well be the ultimate icon of depressed confessionalism, the creator of heartsick classics that have served as emotional blankets to a generation of sensitive souls. But she's no sourpuss.

"I just like beautiful music, and most beautiful music is sad," Mitchell said cheerily one recent evening (she's a late-riser, no interviews before 4 in the afternoon) at an Upper East Side hotel. The subject of her visit to the East Coast is the dark-hued Turbulent Indigo: The album, due out today, is her first collection of new material since the 1991 return to form Night Ride Home, and her first record for Reprise since her 1971 masterwork Blue.

"I remember the first piece that really made me swoon," she says, up on the edge of the sofa, chain-smoking Marlboro Lights and drinking coffee, her straw-colored hair falling over her shoulders.

"I heard it in a Kirk Douglas movie called The Story of Three Loves. It was Rachmaninoff, Variations on a Theme of Paganini. I was just a baby" - 10 years old, in Saskatoon, Saskatchewan, in Canada - "and I didn't have any money. So I would go downtown to the record store where you could go into a glass booth, take the 78s out of their brown paper, and listen to see if you liked them. And I would listen to that over and over again. To this day, it's the saddest and most beautiful piece of music I've ever heard."

It's that kind of melancholy that Mitchell, 50, was drawn to while composing the 10 songs of Indigo, which considers such weighty topics as teenage pregnancy, battered women, AIDS and the ozone layer, and finds a spiritual center in the biblical sorrows of Job. (The title of her 17th album does not intend any association with Blue, Mitchell! quickly points out - it's merely meant to describe the volatile artistic life.)

At home in Los Angeles, she built guitar and piano parts that are central to the album's sparse arrangements, which feature the bass of Mitchell's husband, Larry Klein. (The couple have been separated for nearly three years, but still work together.) Additional nuances are provided by the soprano sax of Wayne Shorter and the husky soul of British vocalist Seal, who contributes to a bittersweet cover of "How Do You Stop," written for James Brown in 1986. All are sung, of course, in Mitchell's often-imitated but immediately distinctive voice, which age and cigarettes have turned dark, but which remains capable of bursts of brightness like those on the despairing "Last Chance Lost."

While the music isn't as free or inspired as that of Blue or Ladies of the Canyon or even Night Ride Home - and it's too weighed down with topicality, to boot - its emotional timbre and acoustic setting will be familiar to devotees of classic Joni. "Every piece of music, as melancholy as it may sound, I play for fun," she says. "It's like petting a cat. I sit up late at night and twist songs into new tunings. . . . It's a very joyous experience. And for the most part, my love of melody tends toward those kinds of complex, emotional chords. You can't put jolly little words to that kind of thing."

Indeed, the words are not jolly. "Sex Kills" - inspired by a "JUST ICE" license plate that Mitchell found herself behind during the L.A. riots - begins as a rumination on justice and devolves into a laundry list of late- 20th century ills ("Little kids packin' guns to school/The ulcerated ozone"). In the extended set piece "The Sire of Sorrow (Job's Sad Song)," Mitchell speaks in the voice of the biblical figure and questions the logic of the Lord ("I've lost all taste for life/I'm all complaints/Tell me why do you starve the faithful?/Why do you crucify the saints?").

And in the song that's likely to garner the most attention, "! Not to Blame," Mitchell plays somber piano and addresses the plight of battered women, her outrage seemingly centered on singer-songwriter contemporary Jackson Browne.

"The story hit the news from coast to coast/They said you beat the girl you loved the most/Your charitable acts seemed out of place/With the beauty with your fist marks on her face" goes the first verse, an apparent reference to tabloid reports that Browne had beaten his girlfriend, actress Darryl Hannah. In the third verse, Mitchell appears to take a vicious swipe at Browne, whose first wife killed herself: "I heard your baby say when he was only three/"Daddy, let's get some girls, one for you and one for me"/His mother had the frailty you despise/And the looks you love to drive to suicide."

Mitchell declines to discuss the lyrics, saying only, "There's no need to reduce such a general subject to any specific person. My songs are composites."

If weighty matters are preoccupying her these days, it doesn't show. Sure, she's dressed entirely in black, but she still has the radiant beauty and vivacious manner of an ingénue. In a photo session, she dances, sings and goofs; she flees down the steps laughing when an elevator full of people see her with cigarette in hand on a nonsmoking floor.

Her playfulness is evident in Indigo's album cover, a painting by Mitchell in which she depicts herself with a bandage around her head. The image is modeled after a Vincent van Gogh self-portrait done after he had removed his own ear. (The first 10,000 copies of Indigo come complete with a souvenir ear.)

The title song and cover are references to a Canadian Council of the Arts conference titled "Making van Goghs," at which she spoke in 1991.

"They wanted to raise up great artists out of women, native Canadians and other ethnic groups. In other words, all these people they consider useless," says Mitchell, who attended the Alberta (Canada) College of Art, and is an accomplished painter and photographer. "I tried to explain that artists the caliber of a van Gogh are born, not made. You can encourage them, but you cannot create a climate as an educator that's going to make a van Gogh.

"This was not a very popular statement," she says, laughing. "But the idea (was) the sand, which, hopefully, became the pearl that is this piece."

Mitchell was born in Fort McLeod, Alberta, and raised in Saskatoon, where she was known as Roberta Joan Anderson. After a bout with polio as a child, she took up painting and dance, then ukulele, making the transition to guitar with the help of a Pete Seeger instructional record.

The turning point was Bob Dylan's "Positively Fourth Street."

"I thought a song was a song and a poem was a poem," she says. "But that particular song was a song about anger that was very well-put. And I thought, 'We can write about anything now. The door is ajar.' "

She took Joni as her stage name - her close friends still call her Joan. The surname came from a brief marriage in the '60s to folk singer Chuck Mitchell.

These days, Mitchell gets back to Canada quite a lot.

"My new boyfriend is a homeboy," she says. "His name's Don Freed. He's a writer-in-residence in Prince Albert )Saskatchewan), and he works with the school system trying to encourage children to write songs. He's only six years my junior, so he's the oldest man I've ever gone out with."

About her relationship with Klein, who is currently playing in Shawn Colvin's road band, she says: "Our friendship is in very good straits. There are still a lot of ways for us to relate musically. We came through it beautifully, actually. I'm very proud of us for that."

Mitchell would like to tour behind Turbulent Indigo - she hasn't hit the road extensively since 1983 - but health problems make it difficult. Rumors of respiratory trouble and even emphysema are false, she says, but she does suffer from postpolio syndrome.

"It's a deterioration of your wiring, basically. I was comparing notes with (singer-songwriter) Victoria Williams the other day, and it's very similar to multiple sclerosis. I'm allergic to a lot of things, and I get tired very easily."

Mitchell is flattered that artists such as Prince and Sting consider her a major influence, and is well aware of the sound-alikes - Colvin, Tori Amos, Jane Siberry, Julia Fordham - that are the vogue on adult-alternative radio. But while she's painfully aware of the difficulties faced by women in the music ("They don't really listen to women, they just kind of look at them"), she hates being grouped with them, whether or not they are her artistic children.

"First of all I've never considered myself a feminist," she says. "It's too 'them' and 'us.' It's too apartheid. I'm more interested in unification. So to be lumped in with all the other women is not my proper place. I think of my group as Leonard (Cohen), Neil (Young), Dylan and myself. And I wouldn't expect these younger artists to strive for the standards that I have as a writer. It's too demanding.

"I've never concerned myself with what was hip or in vogue. Hip is never interesting to me, because it's like a conspiracy. It's a herd agreement. If you're going to be a discoverer, you have to abandon what is hip."