There's no mistaking the elfin figure in the size-4, blue suede mocs who answers the door to apartment 10-O. This despite the fact that her hair, only recently lifted from the pillow, is uncharacteristically swept upward like a kewpie doll's caught in a tornado. Or that, at 4 foot 7, a visitor of average height might be forgiven for looking right over her to the panoramic view of the Hudson River that fills the living-room window.

But there will never be any confusing - and most definitely, no ignoring - that voice.

"Good!" Ruth Westheimer declares by way of a greeting in the singular guttural trill once described as equal parts Grandma and Freud. "You don't have a photographer, so I don't comb my hair!"

As the celebrated sex therapist nears her 84th birthday this week, the voice has aged but certainly not mellowed.

When Westheimer - who fled Nazi Germany as a child - reached the U.S. in 1956, people told her she had to escape that accent. But with a job that paid $1 an hour and a baby daughter to care for, she had neither the money nor the time for speech lessons. Now, Westheimer's delight of the moment is that an actress who will soon play her on stage is actually paying a dialect coach so that she can sound just like Dr. Ruth.

"It's nice to be Dr. Ruth," she says. "Put that down."

It's been nearly 32 years since Westheimer broke into late-night New York radio with "Sexually Speaking," launching a career as confider-in-chief to Americans who, it seemed, had been yearning to share their sexual doubts and fears. The voice that Westheimer found on radio, and in the books and television shows that followed, pushed the boundaries of popular culture, declaring it not just safe, but healthy, for people to speak explicitly about their sex lives.

Westheimer fled Germany at 10, when her parents secured a spot for her on a train taking 100 Jewish children to refuge in Switzerland. Her last memory of home is seeing the faces of her mother and grandmother slip away as the train departed Frankfurt Hauptbahnhof. Both her parents were murdered in the Holocaust.

Raised in a Swiss orphanage, she left at 17 for what was then Palestine, joining the Jewish paramilitary Haganah and training as a sniper. Westheimer's given first name is Karola, but Israelis deemed that too German. She became Ruth, but kept K as a middle initial in the hope that if anyone from her family had survived the Nazis, they might be able to find her.

A few years later, she moved to France to study at the Sorbonne and teach kindergarten. Reaching New York in the 1950s, she settled in the same upper Manhattan enclave of German Jews that had taken in future Secretary of State Henry Kissinger and his parents. She married, became the mother of two and earned a doctorate in the interdisciplinary study of the family. Her research tracked contraceptive usage among 2,000 women.

She might have stuck to academia and counseling if a New York radio executive, bound by law to broadcast public affairs programs, hadn't gone looking for help addressing sex education on the air. On a Sunday in 1980, at quarter after midnight, the baroque notes of a piccolo heralded the arrival of a voice synced with a sexual revolution come of age.

"No one captured the imagination of the country like she did," says Pepper Schwartz, a professor of sociology at the University of Washington and the author of numerous books on sex and relationships. "That sort of mature, whimsical voice that she had, reassuring and knowledgeable, talking to you like your fantasy grandmother would ... really gave the country permission to have this dialogue in a new way."

In the years since, "there's been a generation of young people that have sort of taken the message and run with it," Schwartz says. Americans began exploring the possibility that recreational sex could also be responsible sex.

On those early broadcasts, Westheimer repeatedly counseled listeners to make sex part of a committed relationship, advocating monogamy and marriage. That message now sounds either timely or quaint, depending on your point of view, in a day when people have blind trysts via cell phones. But Dr. Ruth is not changing her pitch.

"I have been old-fashioned and a square and I'm still old-fashioned and a square," she says. "In our culture, most people want to have a significant other that means something to them in their lives."

She deplores sexting as a "catastrophe," and warns that men who rely on Viagra will find their advances rejected unless they've also remember their partners' birthdays and anniversaries.

At the end of a recent talk at the National Council, the questions are fairly tame. Asked for advice on how to find a man, Westheimer - whose husband, Fred, died in 1997 - says: "If I had an answer to that, at first I would take the guy for myself."