YOU BEGIN "Words drawn in water," the new audio walk devised by Canadian artist Janet Cardiff, by sitting on a bench in the lobby of the Hirshhorn Museum and Sculpture Garden. Speaking through headphones, Cardiff introduces the philosophical basis for her (and your) imminent stroll by discussing water, memory, change and the art of James McNeill Whistler. Then she instructs you to leave the building through a door whose use is normally restricted to emergencies. In a city whose major institutions have been virtually locked down since Sept. 11, 2001, this is an invigorating moment. It's also the headiest one the piece provides.

Part of the charm of "Words drawn in water" is not knowing exactly where Cardiff is going to lead, even if the possibilities are not exactly endless. (Since the walk lasts only 33 minutes, it's clear that you're not leaving the Mall.)

So before you read the rest of this review, put down the Weekend section and take the Metro to L'Enfant Plaza. Leave via the Seventh Street and Maryland Avenue exit, walk a half-block north to the Hirshhorn and enter the building. A booth near the front door -- assuming you arrived between 11 and 3 Wednesday through Sunday -- will temporarily swap your ID or credit card for an iPod and headphones. Take that deal, complete Cardiff's narrated itinerary, and then return to wherever you were and continue reading this article.

Did that paragraph seem bossy? Well, that's one of the problems of the audio-walk format. The first purely audio work in the Hirshhorn's "Directions" series, "Words drawn in water" guides you away from the customary museum experience, into the outside and a realm of new possibilities. Yet you go only where Cardiff walked before, carefully following her instructions. (She even instructs you to stop for cars at crosswalks where pedestrians have legal right-of-way.) If you don't walk the correct path, you'll soon be gazing at something completely different from what she's discussing. Although the device providing the artist's commentary is an iPod shuffle, there's no shuffle function in this artwork. (Also no rewind, by the way, so don't space out.) Just walking through the Hirshhorn's galleries offers more potential serendipity than following Cardiff's prescribed course.

Accept that limitation, and "Words drawn in water" is appealing, if only for its novelty. For those who don't really know the area near the Hirshhorn, Cardiff's tour might even offer a few revelations. Longtime Washingtonians -- and visitors who read guidebooks -- know that James Smithson's remains are interred near the entrance of the original Smithsonian building, but some audio-walkers will be surprised to encounter the crypt. The tour's final stop also may be unexpected, although not to anyone familiar with the museums on the south side of the Mall. As soon as Cardiff mentions Whistler, it's obvious that the tour will head in the direction of the Freer Gallery, home of the flamboyant Peacock Room that Whistler designed and that was ultimately relocated, just like Smithson's bones, from Britain to the District.

Cardiff isn't simply a tour guide, of course. She connects the sites along the way with things we can't see, including personal recollections and historical and political musings. "This city makes me paranoid," announces the artist, an opponent of the latest U.S. invasion of Iraq, as phantom helicopters buzz around her voice. She contemplates the historical context of landmarks that are visible, including the Washington Monument, and ones that aren't, such as the Vietnam Veterans Memorial. Her thoughts stray to such topics as her first visit to Washington 20 years ago. She also attempts to mingle reverie and satire, as when she announces that the Hirshhorn's outdoor sculpture collection will soon "be gone, I heard, sold for the war funds."

Cardiff's cool delivery and deadpan quips recall the work of Laurie Anderson, another conceptual artist who works primarily with sound and words. Both are prone to using the art-world buzzword "about" to pump a little profundity into the most banal of observations. After sharing bits of conversation she recorded with people she encountered while devising the piece, Cardiff explains that "I like to record people. I think it's about trying to stop everything from disappearing." Uh, no kidding. It's only that "about" that separates Cardiff's pronouncement from the aesthetic doctrine of anyone who has shoeboxes full of baby snapshots or shelves piled with videos of family picnics.

Unlike Anderson, Cardiff is not a musician. But she skillfully employs ambient and borrowed sound, as well as some mellifluous phrases from African American singer and political activist Paul Robeson, who's another of the piece's thematic markers. The sound mix is so rich that it might be worth a listen while sitting still, although Cardiff's more banal remarks surely benefit from the distraction that comes of walking her designated course while she raps.

That's the burden of conceptual art: It requires both innovative form and novel content. This piece certainly has the former. The audio walk is essentially Cardiff's invention, and she's mastered many diverse elements, including a dab of prophecy. (Will a jogger pass you just when she says? Probably.) Too bad that Cardiff's commentary on molecules, history and such rarely reaches the level of high school cafeteria chatter. Philosophically, "Words drawn in water" is a walk on the mild side.

DIRECTIONS -- JANET CARDIFF: WORDS DRAWN IN WATER -- Through Oct. 30 at the Hirshhorn Museum and Sculpture Garden, Independence Avenue at Seventh Street SW. 202-633-1000. Open daily except Dec. 25 from 10 to 5:30.

Tom Healy and son Michael view a Rodin piece in the sculpture garden during Janet Cardiff's audio walk "Words drawn in water" at the Hirshhorn Museum. Brothers Michael and Matt Healy sit on a Mall bench -- per Janet Cardiff's instructions.