You start with the script. You pick the cast. Then you have what producer Diane English, creator of "Murphy Brown" and the new "Ink," calls the third big element of a television hit.

The people watching it.But we're not talking about the viewers, or the Nielsen points.

We're talking about the live audience, whose members get to laugh about 15 times during your average three-hour live taping session for your basic 22-minute sitcom.

"On show day, it's a live audience that the actors feed off of, and the actors really respond to them, and a real bond forms between the audience and the people on stage," said English, who was brought in this season to save "Ink" when even its co-stars, Ted Danson and Mary Steenburgen, were rejecting the show.

James Burroughs, the multiple-Emmy-winning director and producer best-known for his work directing "Cheers," calls the audience "irreplaceable."

"It's the reason I wanted to get into this. I came from the theater, and it's all about opening night," he said.

"Every Tuesday (taping) is an opening night. The audience is invigorating."

In return, studio audience members get to see how a television show is made, watch their favorite stars up close and maybe see themselves on television when the episode airs.

Most live-audience sitcoms are taped on Tuesdays and Fridays. Game shows and talk shows also usually work in front of a studio audience, while dramas don't. Though having an audience in place costs for recruitment, transportation, ushers, a warm-up entertainer's salary, security and sometimes a nominal fee paid to audience members, the expense generally totals only $5,000 to $10,000 per taping out of a $1 million weekly budget for the average sitcom.

While the budget is small, the power can be sizable. Audience members can make directors, producers or writers change the shows. If the sample doesn't laugh, lines or entire scenes are reworked.

"If a joke dies, you can always replace a joke - and I will," Burroughs said.

For the most part, audience members can select the show they want to see. "Home Improvement" is popular because it shows a portion of the studio audience during its "Tool Time" segment. "Friends" also currently has a waiting list. Other shows, such as "Seinfeld," rarely have audience openings, opting for friends, family and "industry types" in its audience. But most shows are open - and free.

Audiences Unlimited in Universal City is the main service hired to find people to fill the seats. The other major player is Paramount, which handles its own shows. Audience Associates in West Hollywood also provides seat-filling services, specializing in snagging tourists at spots such as Melrose Avenue, Venice Beach, Santa Monica Pier, Third Street Promenade and Mann's Chinese Theater in Hollywood. This company also works with about 200 hotels. NBC and Universal Studios recruit at CityWalk.

To drum up a crowd, an audience service might be hired to arrange a full house in a hurry when a show is not taping on its usual day or when no one has asked to get in to see it. These "professional" audiences are paid a few dollars a head.

"We deal mainly with groups, and we have a lot of groups that will come on short notice," said Steve Sheets, coordinator of guest relations for Audiences Unlimited.

When shows are canceled, the company will try to contact audience members and reroute them to a different show.

"We're always busy looking for people," Sheets said. "We usually don't have too much trouble after the shows air. Pilots are real hard unless they are real names that people want to see. It's tough sometimes when we are working with a new production company and there is nobody recognizable in the cast."

Once a sitcom audience is in place, the laughter often is edited or "sweetened." An example would be when the acting is better on a second take, but the laugh was more genuine during the first take when the audience was surprised by the joke. The better laughter might be inserted into the take with the better acting.

And sometimes laughter is balanced out or pumped up, or canned laughter might be added. Occasionally an audience laughs too hard "even at the straight lines" and has to be toned down, English said.

"I tell them not to try to identify their own laughs," said former "Seinfeld" warm-up man Pat Hazell, creator and star of a replacement show called "The Archers of Omaha," which is waiting in the wings. "If you laugh, `Hey this is Bob Johnson from Toledo, Ohio,' they cut 'em out."

The first thing an audience notices is that it is "the fourth wall." The sets - life-size kitchens, offices, bedrooms, living rooms - have three walls. In between the set and the audience are four cameras and scurrying personnel.

"You can see a lot of what goes on behind the scenes," Sheets said. "There are 90 people on the floor, and cables, and so many production people."

Besides seeing the directors direct, the cameramen shoot and even that person with the "take" slate, audience members get to see gaffes and ad libs.

On "NewsRadio," cast members Joe Rogan, Phil Hartman and Andy Dick sometimes go into the audience during long breaks.

"One time, Dave Foley had to get into a dress," Rogan said, "and it took a long time, over an hour, so I climbed into the crowd."

During tapings of UPN's "In the House," series star LL Cool J raps to the crowd, and co-star Alfonso Ribiero does a little breakdancing.

In some cases, you hear dirty language that is off the script. Tim Allen seems especially comfortable on stage and often gets a bit off color.

"It's the things that you don't expect that are some of the funniest things," said Dave Gonzalez, 33, of Pacoima, who was in a recent "Home Improvement" audience. "I found myself laughing more at the mistakes than the actual lines. Sitcoms are so predictable, I knew how it was going to go."

Gonzalez, coming from the San Fernando Valley, where many shows are produced, is not the typical audience member. Nobody is. The audiences usually are a mix of European tourists, college frat guys and groups trying to raise a few bucks. With scenes often done more than one time, a taping can make for a very long evening.

"Luckily, everything was done in one or two takes. I enjoyed myself," Gonzalez said. "It went by pretty fast."

But even after a three-hour-long evening with an audience, the process actually bogs down after the audience leaves. Usually there are some extra shots to take, called pickups, which are the same sets or situations from different angles. These might be used to open a scene, for example.

"Pickups take forever . . . the whole energy grinds to a halt," English said. "There's no energy to it anymore. I've done shows with audiences and without audiences and, by far, it's much better with."

"A show without a studio audience is not as good," agreed "NewsRadio's" Rogan. "You can see the difference. Everybody is pumped up. And a lot of times they have already seen everything twice and have to see it a third time.

"I've seen other shows when they try to keep people from leaving. I've been to `Party Girl' (already pulled from the Fox schedule) and people were leaving like the place was on fire. They were trying to hold people in their seats. On `Hardball' (his last series), we had a hard time, especially because the director was slow."