Les Waters has built a strong reputation as a director of the new: "When I go into a bookstore," he said the other day before a rehearsal of Sarah Ruhl's In the Next Room, "I'm always interested in what's just come out." And Waters also has an excellent reputation as a director of plays by and/or about women: "I can't say I go on the lookout for stories about women," he explains. "That's just what I tend to be interested in."

Neither his experience with new work nor his gift for staging stories involving women, however, provided him with the exact blueprint for doing the Ruhl play. "It's a unique animal," Waters said. "You have to balance a quite delicate sensibility with the tougher practical side of getting the story successfully on a stage. That's very new for me."

And what's at the heart of the technical challenge? "The play has action taking place simultaneously in two rooms," Waters explains. "You have to make sure that one doesn't overwhelm, or distract from, the other." The director says he's grateful to have done the play already, earlier this year, in a production at Berkeley Rep, where he is the Associate Artistic Director. "It took hours and hours to get the balance right in the doctor's operating theater - the changing of sheets, the turning off and on of lights."

In addition to the mundane details, there is, said Waters, whose next assignment back in Berkeley will be a Naomi Iizuka play that, like the Ruhl, is set in the 1880s and involves a new technological device, the question of tone. "You have to move from one room, where someone may be having a terrific orgasm, to the other room, where someone may be feeling incredibly lonely. If it's played too broad - and this is definitely not a farce or an all-out comedy - then the emotional impact isn't right: a glib tone would make it easier for an audience, for example, to dismiss a woman character who feels a failure as a mother."

Waters, who worked with Ruhl a few years ago on a popular and acclaimed production of her Eurydice, adds, "The question of tone is also crucial because [In the Next Room] is a study of the intimacy of a marriage." The director added that the overall intimacy of the piece, emotionally and sexually, requires care in casting. "You have to make sure that you're working with people who are quite fearless."

Waters says that he's enjoyed watching audiences since getting his first job at London's Royal Court Theatre in the 1970s, and that observing the audiences at In the Next Room has been especially helpful. "When the vibrator is used in the play for the first time, there can be a kind of frisson in the house. Then the audience tends to relax a bit."

I will save a full discussion of the play's vibrator device for another blog entry; Waters says that he knew what a vibrator from the story's timeframe, the 1880s, looked like from reading The Technology of Orgasm, the Rachel Maines book that was one of Ruhl's sources of information. But Waters didn't know what one sounded like. "There's a museum in Minneapolis that has vintage vibrators, but apparently nobody can turn them on."

BRENDAN LEMON is the American theater critic for the Financial Timesand the editor of lemonwade.com.