Mike Herter's brow was furrowed into a set of startled lines last week when a cold inquiry punctured the hot blast of gospel music throbbing through the "Music in Metropolitan Washington" exhibit that is part of the Smithsonian Institution's Festival of American Folklife.

"This woman came up to me," said Herter, manager of the exhibit, which runs through Sunday on the Mall, "and she said, 'Excuse me, but can you tell me when any group here will be playing any American music like "America the Beautiful"?' I just looked at her and said, 'Ma'am, every group we've got here is singing that song in their own special way.' "

For this festival, the feeling is not only all-American, but all-Washington as well. Every song performed by every one of the 20 groups in the "Music in Metropolitan Washington" exhibit is indigenous in some way to the nation's capital.

This means that no matter what the genre -- be it reggae, blues or bluegrass -- the music is tinged with the flavor of this city. Phrasing (various types of "call and response" in a gospel chorus), interpretation (rap delivery in songs from the go-go vein) and even how long a particular note is held are forms of stylization the groups use to make their music the city's own.

Judy Goodrich, a volunteer working backstage, says groups such as the bluegrass-based Potomac Valley Boys and the reggae-oriented Jah Honey and the Unconquered People must be heard to be understood. "They are like nothing else," she says.

Many would scoff at the notion that Washington has a type of music it can call its own, but Herter, 35, is not among them. He believes passionately in the area's musical history and heritage, and wants it to be recognized. And he's not a local musician. In fact, he's not even a local.

The Massachusetts native is thankful, then, for the position of exhibit manager. It lets him show people that even though "Washington's music scene isn't as identifiable as, say, New Orleans' or Chicago's ... it's very, very strong."

Washington has an ethnic diversity rare among American cities, he says, and the Smithsonian folklife exhibits reflect that. Gospel, blues, calypso, Afro-Cuban, reggae, Bolivian, eastern Indian, bluegrass and southern mountain music are all represented.

So if asked what music is Washington's own, what would he say?

"Patchwork," he quickly replies.

Herter came to the Smithsonian in 1976 upon his graduation from Harvard. He worked for two years editing in the organization's film department, every summer participating in the Folklife Festival. Even when he moved to New York to pursue an acting career, he says, he couldn't get it "out of my blood. So every year, my wife Penny and I come back and work here. It's our vacation. A paid one, really, because I get $1,000 a week. But the money is not the important thing ... .

"Along with increasing education among visitors," he says, "this exhibit is also increasing community spirit {among musicians}. I've seen stereotypes melt ... Reggae bands, for instance, sitting down and really listening to gospel groups where maybe without this opportunity they wouldn't have."

Social issues have also come up on the concert stage. Last week, he says, "there was a gospel group on stage -- Mattie Johnson and the Stars of Faith -- and Mattie made this really unexpected plea. She asked all the children in the audience under the age of 20 to come down and sit at her feet. Of course, most of the kids were real shy, and they wouldn't at first.

"But then, all of the sudden, a huge crowd of kids just came up, and then all of them under the tent did. And she looked out over them and very quietly said, 'I want to talk to you all about drugs.' She talked for a while, then the group sang a song relating to her message. So what we had was something social, something educational and something musical."

He pauses. "And you know, I don't think you can ask for more than that anywhere."