The playwright Bess Wohl calls herself a true believer in New Age spirituality. She reads the books, she does the yoga, she tries to meditate. So when a close friend asked several years ago if she wanted to go upstate from New York City for a weekend-long retreat led by the Buddhist nun Pema Chodron, a teacher they both admired, it was an easy yes.

“I sort of thought of it as more a girls’ bonding thing than necessarily a spiritual thing,” said Ms. Wohl, who wrote the sandwich-shop comedy “American Hero” and the book for “Pretty Filthy,” the Civilians’ recent musical about actors in the pornography industry. “I showed up with, like, my bottle of red wine and my snacks.”

That wasn’t quite the right vibe for what turned out to be a silent retreat, much like the one a half-dozen seekers embark on in “Small Mouth Sounds,” Ms. Wohl’s new play, which has been extended through April 25 at Ars Nova. Aside from the unseen teacher, who lectures from offstage, its characters say almost nothing. Most of the play is written in the form of stage directions, and the audience bases many of its assumptions on nonverbal cues.

Critics have hardly been silent in their enthusiasm. In a review for The New York Times, Charles Isherwood praised the writing (“intrepid”) and acting (“superb”), as well as the direction by Rachel Chavkin (“precise”).