Voice Lessons, Zephyr Theatre, 7456 Melrose Ave., Los Angeles 90046. Performances Fri.-Sat., 8 pm; Sun., 7 pm; through May 17. Tickets: $25. Call 323.960-7711 or visit www.plays411.com/voicelessons.

Laurie Metcalf and French Stewart are sweating. Not because it’s an unseasonably warm 80 degrees outside the Zephyr Theatre but because they’re running lines for the final tech of Justin Tanner’s world premiere play Voice Lessons and the air conditioning is turned off. The heat doesn’t stop Metcalf from attempting a fake gazelle leap while wearing the truly cringe-worthy garb her blue-eye shadow community theatre actress character has chosen for an Ado Annie number.

Timing piano sound cues clad in a rumpled white t-shirt and nondescript pants, Stewart plays the intellectual vocal coach Metcalf’s delusional character hires to make her a star. Noting the presence of an outside observer he cracks, “She probably thinks this is what we wear every day.”

The two are veteran explorers of Tanner terrain. Stewart dates back to the core Cast Theatre company days circa 1989 while Metcalf caught Tanner fever watching an early incantation of Pot Mom. This is her fifth Tanner play and third with Stewart after Pot Mom and Still Life With Vacuum Salesman both at the Cast. Los Angeles audiences last saw Stewart in Space Therapy in 2007 at the Zephyr with Maile Flanagan who now also rounds out the Voice Lessons cast.

The play returns Metcalf to her small theatre roots (honed during the birth of Chicago’s famed Steppenwolf Theatre), following a Tony Award nominated performance opposite Nathan Lane last year in November. The Broadway run was sandwiched in between her 2007 Ovation Award winning role in Jane Anderson’s A Quality of Life at the Geffen Playhouse and a subsequent run at the American Conservatory Theatre in San Francisco last fall.

Seated in the Zephyr’s lobby following a tech rehearsal helmed by the play’s co-director Bart DeLorenzo (who shares duties with Tanner), Metcalf and Stewart are each other’s physical comedy Siamese twin. The two met when three-time Emmy winner Metcalf (Roseanne) did a guest stint on Stewart’s show Third Rock From the Sun and have since done several other projects including the animated series God, the Devil and Bob.

Having now shadowed each other over all sorts of acting terrain, both admit they share a common work ethic and comic sensibility.

“I think there’s a trust in that you know they’re not going to go nuts,” laughs Stewart. “That they’re a sane person!” Metcalf chuckles as he continues. “It seems like a small thing. But I also think we have the same feelings about things, being if we enjoy them then it’s going to carry over.”

“We have a similar take and similar amusement level,” Metcalf concurs. “Definitely.”

When told he once called her the “gold standard” of acting, she immediately blushes and adopts a coy Scarlett O’Hara demeanor, uttering, “Why, Mr. Stewart!”

“A lot of my problem is that I’m having to straight man it throughout this whole thing and watch her go uncorked,” he admits. “And when Laurie Metcalf goes uncorked….” He laughs. “A lot of it is just keeping yourself together! This is a whole new challenge. I just have to keep reining her in.”

“One of my favorite combos to play in a character is a lot of attitude with nothing to back it up!” admits Metcalf laughing. “She’s sort of a luxury to play because, and I might even be using the wrong term, I think it’s a pure id. There’s no monitor. I don’t even know if there is a thought process involved with her! Anything she blurts out is what she feels in the moment.

“The character amuses me to no end. All you have to do is dress it up, wind it up and set it out there on stage.  It will eventually implode as it is supposed to!”

A big fan of Tanner’s writing, Metcalf hosted readings of the Voice Lesson’s script at her house where Stewart joined them later in the process. When Tanner finally lined up the Zephyr to mount the production, she admits she found it impossible not to be involved because “it’s the kind of critter I like to scratch around in. I like his dialogue,” she confesses. “I like how contemporary it is. I like how selfish all the people are, which sounds negative I guess, but they sure do go for what they want. They go full steam ahead and I admire that in a character!”

“It was just a situation of everyone thinking this could be really fun,” adds Stewart.  “There’s a part of it that’s a love letter to the outskirts of theatre. The great thing about his plays is they’re about an hour and 10 minutes. It’s like once the train leaves the station that’s it.

“This is my 10 or 11^th play with him. It’s always the same thing. You do them and it’s a fun process but it’s also an exacting one. It exacts a certain payment. So you always say, that’s it. This is the last one for awhile. And then he’ll call you in two years and say oh, just read this. And you say, I gotta do this!”

Despite extensive TV, film and theatrical credits, both admit a deep reverence for the kind of small theatrical spaces like the Zephyr that gave them their starts.

“It’s a throwback, a comfortable one to me, of 30 years ago,” Metcalf enthuses. “Where we’re going to make our own costumes, buy our own costumes and bring our own props. It’s very collaborative.” Metcalf’s daughter Zoe Perry in fact is on board helping costume her mother’s zany on-stage persona among other duties. “It’s just a system I understand and feel very comfortable in. I don’t think of it as any more than that.”

“I feel the same way,” adds Stewart. “It’s birthday cake. It’s one of the few things you can do in your life that’s pure enjoyment. I love these little theatres on Melrose with these seats and these funky floor plans. This was the same thing I was doing when I was 17. You always think you’re using them as a means to get someplace. And then you get someplace but you keep coming back to them. Then you realize there’s something really comforting about it. It’s such a nice thing to have. Because it’s always the same but it’s not.”

When asked what the play is really about, the two start to laugh.

“What did we decide?” says Metcalf looking at Stewart. “It’s Educating Rita where no one learns a thing!”

“It’s really the best description I’ve heard of it so far,” he replies.

“That’s kind of it,” she adds.

“It really is,” he says. “Because by the end they’ve changed but only in a way that’s more aggravating.”

French Stewart and Laurie Metcalf in Voice Lessons