"It's the baby's nap hour," says Liz Phair, the miniskirted, potty-mouthed rocker who's the darling of feminists and frat boys alike. "I have some time to talk."

We've reached Phair on her car phone, driving home after a jog. She's heading through traffic to her suburban Chicago home, where husband Jim Staskauskas, 18-month-old son Nick, and Nick's binky await.

Just another day in the life of the famously 5-foot-2 sex goddess.

"Motherhood has changed me a lot," says Phair, 31, whose self-described small, slender-hipped body went through 32 hours of labor to produce a broad-shouldered, 8-pound, 7-ounce boy. "It was instant adulthood, in a positive sense. It makes me feel like a real human being. I feel good about doing something well that was hard to do. It makes me want to do more things that are hard and do them well."

Nick will accompany his rock-and-roll mama on the Lilith Fair tour, where Phair will play a total of 16 dates, including Thursday's gig at Jones Beach. The headliners for Monday's show at the PNC Bank Arts Center in Holmdel and Wednesday's at Jones Beach will be the same: Sarah McLachlan, Natalie Merchant, Indigo Girls, Missy Elliott, and Tracy Bonham. On Thursday, Phair will replace Bonham.

Phair jokes that touring with the all-women summer music show will give her an opportunity to "compare bras," but she's serious when it comes to her desire to take part.

"I was really bummed they didn't ask me last year," Phair says. "I've always hated being on the road because it was all guys. I get so tired of hearing guys talk about rock. I want to have peers to call and say, 'Doesn't this [stink]?' But all my friends are lawyers and therapists and graduate students. They never know what the hell I'm talking about. Being with women on Lilith gives me friends. And no more rock talk. I can't take it. As soon as we get out of Lilith, we'll be back in guy world."

Phair fans who'll miss her Lilith appearances can look forward to a solo tour with a full band in the fall to support her first album in four years, whitechocolatespaceegg, due in stores Aug. 11.

"I had a very vivid dream while I was pregnant that I had an album out called whitechocolatespaceegg," Phair explains. "I was sitting down at a table to sign copies of it, and people were lined up. They kept saying to me, 'I really like your album.'"

"It was a strange dream for me because I usually have very active dreams, like I'm fighting in a war or something. But this dream wasn't about action. It was about a state of mind. It was all very soothing. I was impressed with this dream, but I didn't push whitechocolatespaceegg as the name of the album. I renamed it many times, but people kept saying to me, 'What was that name you had before?'"

The album, dream-inspired name and all, may be Phair's best. Earlier this year, both her previous albums -- Exile in Guyville (1993) and Whip-Smart (1994) -- went gold, with sales of more than 500,000 units. ("We ate cake," Phair says of the celebration. "It was fun.")

But whitechocolatespaceegg is the songstress' first effort since she became a bona fide rock star, and she doesn't disappoint. Her trademark anything-goes lyrics -- raunchy enough to make Aerosmith blush -- haven't been softened by motherhood (in "Johnny Feelgood" -- a song whose lyrics actually can be reprinted here -- she sings, "I never realized I was so dirty and dry/Till he knocked me down, started dragging me around in the back of his convertible car/And I liked it/I liked it more and more"). While Phair's charming dirty-girl-with-a-guitar simplicity remains underneath it all, the production (by Phair, Brad Wood, and Scott Litt) is more ambitious, and the instrumentations are more lush, more layered, and more daring than the decidedly lo-fi concoctions of Exile in Guyville and Whip-Smart.

"I have this really great band now," says Phair. "I used to have very bad stage fright, and it was because I felt inadequate about being a performer. I was a writer, not a performer. I was frightened by all the attention, but I don't feel that way anymore, and a lot of it has to do with the band.

"Also, I've faced up to the fact that I've always loved to sing. I always felt that my voice wasn't good enough. It wasn't angelic. Now, I've taken steps to be good enough. I take voice lessons. My voice coach will be at Lilith with me. It's funny. I was a rebel in my 20s, but at 30, I'm like, OK, when did I stop learning? It's exciting to go somewhere and have somebody help you. It keeps you feeling young and alive."

So does little Nick, who Phair says is in that stage where "everything is discovery" and strolls around the block can take hours.

And even though the labor was difficult, Phair says the pregnancy was a time of unprecedented creativity for her songwriting.

"Part of me awakened that had been dormant since childhood," Phair says. "I had all these creative impulses. Things were happening to me that didn't happen because I was doing it, they came of their own impetus. Feelings were coming up that I didn't have a hand in. They were from a much deeper part of myself. I was dreamier."

Of the 16 songs on whitechocolatespaceegg, Phair says four were written during that time -- "Headache", "Only Son", "Baby Get Going", and "Love is Nothing".

That dreamy, creative energy is gone now, Phair says.

"Life is back," she says. "It's OK. My new job is to be extroverted. It's like going into battle in a funny way."

Phair's cell-phone connection starts fritzing, and she pulls the car over to chat some more. When the line is interrupted again, she hangs up.

A minute later, Phair calls back from a supermarket pay phone.

When asked about possible siblings for Nick, Phair doesn't hesitate.

"I want more kids," she says. "Right now, though, I need to work my album. As far as the fall tour, I'll play it by ear. But if I didn't do what I have to do as a mother, it wouldn't work."

Just another day in the life of a 5-foot-2 sex goddess -- with a kid.