AUDIENCES. Sometimes they're more fun than the show. If Washington is a melting pot of nations, it is also a bouillabaisse of audiences.

There are avid audiences and haughty audiences. There are dinner-jacketed audiences and T-shirted audiences, audiences that whistle, stamp and shout, audiences that stand and clap frantically for encores, and audiences that scramble up the aisle while the curtain is still closing. There are audiences that chatter incorrigibly through the whole performance and audiences that spend the evening buried in the program notes. There are audiences that bring a radio to a football game and listen to another game on it. There are audiences that riot and make history. There are jolly audiences, sulky audiences, whooped-up audiences, bored audiences, self-admiring audiences, reverent audiences, arrogant audiences, conspiratorial audiences . . . an audience for every occasion. And then some.

At the season opener of the Seventh Street gallery strip, you are what you wear.

Leather jackets, harem trousers, draped sweaters, cowboy boots, tux-and-jeans, combat pants, windbreakers, punk haircuts, punk torn T-shirts, punk stained pants, punk miniskirts, business suits and a gorgeous white jacket with a big red rose fight their way up and down the staircases at Washington Project for the Arts, throng the studios and overflow onto the street.

They are mostly couples, quite a few gays, and the drinks they carry range from highballs in real glasses from Harry Lunn's full bar to jug wine in plastic from someplace on the third floor. Everyone is shepherding a drink, guarding it from the crush with hand cupped in front, like a lighted candle. Everyone talks at once while staring around the room at everyone else except the one they're talking to. Painter Leon Berkowitz is there, and Zbigniew Brzezinski, and Frances Fralin of the Corcoran, and artists and models and patrons.

Man in baggy gray sweatshirt to woman in mini and tights: "Oh, that New York and Washington thing is such a bore. What does New York have except more of it?"

Crewcutted man with sweater draped around neck to ditto: "Do I know you?"

Well-dressed woman to well-dressed man, about to enter a roomful of modern paintings: "Well, this is where we hit the threshold of pain."

The dinner theater is the road show of the old-fashioned classic urban dinner date, the fancy restaurant followed by a Broadway hit.

We are about to see "The Mousetrap" at the King's Jester theater in Silver Spring. The crowds are handled with practiced ease: There are no long lines at the rather ambitious buffet, and your drinks and soup are brought to your table.

Nearly everyone in the house seems to be on a date. A few are double-dating. One guy sits alone at the bar. The men take off their jackets, revealing short-sleeved shirts. The women are in cocktail dresses. Two couples are talking with cozy animation about Pac-Man. Now it is the Redskins. Now stretch marks. The chatter level builds quickly until it is interrupted by the chef taking a bow and, as we move to the theater in the next room (unraked, with folding chairs), we are told that King's Jester will soon do "Luv" and "The Elephant Man."

This is very offbeat for a dinner theater, which usually goes for musicals and drawing-room comedy. Many couples appear to be here for the first time. (At the Hayloft, many patrons come to every show, sometimes more than once. One man said he came exclusively for the buffet but always found the play very pleasant to doze off to.)

This drama goes slowly indeed. Someone murmurs, "Now I see why it's been playing in London for 35 years: They're still doing the first performance." People whisper among themselves. There are hardly any laughs but a lot of craning to see the traditional tiresome Agatha Christie bits of business: people surreptitiously stuffing things into drawers and hiding gloves.

In the second act the audience perks up. They have brought wine carafes and drinks from the bar, and during tense moments glasses get kicked over and roll around underfoot. The audience, in fact, is the liveliest part of the evening. As soon as the lights go up they resume their animated conversations.

Now take a look at the people who do make the effort and go into the city for a show like "1,000 Years of Jazz" at Ford's Theatre. This audience has invested considerable money in the evening and is going to have a great time no matter what.

A good group, this. It's an occasion for most of them, maybe someone's anniversary, and they have put on their brightest threads. You see some leisure suits, scarlet jackets, white shoes. Perhaps because they know in advance that they will be entertained by pros, they aren't too critical, aren't bothered by preconceptions or affectations. They laugh and cry on cue and will remember the evening long after its creators have lost it in a whole skyful of bright evenings.

The trouble with the movies is that the audiences think they're watching TV at home, jumping up to get more popcorn every few minutes, shifting seats, talking, talking, talking.

Believe it or not, this can be fun. Go to the kung-fu pictures at the American Theater in L'Enfant Plaza some Saturday. A friendly bunch, about 90 percent oriental and 10 percent black. Families with small children. Kids with bushels of popcorn. Older couples with sandwiches in bags. There's a steady mutter of soft conversation except in the big suspense moments. When the big final fight starts, they tend to cheer.

This is a wonderfully responsive audience. They laugh at the jokes, even the ones that don't come onto the subtitles.

The exact opposite are those shadowy figures who slip into the D.C. Playhouse to see X-rated films so aggressively boring that they are giving smut a bad name. These guys are all singles and all sit in different rows from each other and never laugh. And some of the stuff that goes on up there is pretty funny. Some scuttle out the back exits, some out the front, onto 15th Street. You wonder what they would say to colleagues from the office who happened to be passing by.

But you haven't really been to the movies until you've been to "The Rocky Horror Show," still packing them in after five years on Fridays and Saturdays at the Key Theatre.

This is not an audience; it's an art form. You remember hissing the villain? These people chant a ritual response to almost every line in the picture. When someone says, "This calls for a toast," the audience throws toast at the screen. For a wedding, they throw rice. For a thunderstorm, the front half huddles under newspapers and the back half squirts water pistols at them. And then there are the costumes . . .

The Kennedy Center has its own little world of audiences, from the somewhat adventurous Terrace Theater crowd to the good old steady National Symphony Orchestra subscription concertgoers.

The only thing they all have in common is the barbarians who rush for the door as the last note is still being sung. These creatures are saying something about our culture, no doubt. There they sit, through the whole evening, thinking only of getting their cars out of the garage. Why don't they park a few blocks away and walk? Why do they come at all?

Applause, after all, is not simply for the benefit of the performers. It is a necessary catharsis for the audience, an expression of its exaltation, joy or whatever high it has been lifted to. When Pablo Casals gave his first cello concert after years of silent protest against fascism, he played in a church. The audience was not allowed to clap. People who were there said it almost drove them crazy, so desperately did they need to cheer and jump up and down.

So if you habitually like the show but don't stay to applaud, you probably need therapy by now.

On the other hand, there are those who insist on clapping at the odd leap in ballet. The other night, when Alvin Ailey's brilliant dancers were working through a lovely sinuous series of human body patterns in the astonishing "Treading," a few people kept trying to applaud at every turn.

Now, there are certain kinds of ballet where this works just fine. Certain numbers are designed as competitions, and first one, then another soloist or pair does some wonderfully difficult bit, and the applause comes in ever greater waves, like the "Ole's" for a bullfighter's veronicas. But this mindless kneejerk clapping for each jete' in a serious ballet . . .

Most NSO concert audiences are mannerly and tame. Now and then some individual will stand and clap when no one else is standing, and a few -- probably veterans of the 20th Century Consort audience, which judges the music very severely indeed -- will hunch with folded arms while everyone around them is going bananas, but generally they sit there quietly and take their medicine.

Sometimes the audience runs the show. In Everyday Theater's "Dog Eat Dog," a sort of psychodrama about social problems -- in this case, crime -- the audience, which often includes everything from jurists to social workers to ex-convicts (in fact the work will be performed at Lorton this winter, after the company returns from a tour in Atlanta), discusses the situations depicted, and the discussions get pretty hot.

Then there is the notorious La Scala audience in Milan, which for generations could make or break an opera singer with its shouts, whistles, booing, stamping and cheers. Wasn't it in Milan that the young Caruso, an understudy, was hustled on to replace a booed tenor, but was drunk because he hadn't thought he would be called? Sang one glorious aria while staggering about the stage, was yanked by the management which tried to put the original tenor back on, only to have the audience yell "l'ubriacone!" demanding "The drunk! The drunk!"

And sometimes an audience, even the politest, even the most conventional, will rise to an occasion.

At the premiere performance of Beethoven's stupendous Ninth Symphony in Vienna in 1824, Beethoven himself conducted. When it was finished he remained standing, hunched over, spent, gazing down at the score. Totally deaf, he couldn't hear the hurricane of applause.

Finally the soprano soloist, tears streaming down her face, came up to him and gently turned him around so he could see them, on their feet, all of them, the whole house, cheering. And finally, inspired, they pulled out their handkerchiefs and waved them for him, a blizzard of white handkerchiefs that filled the hall.

Now there was an audience.