Susan Cain, a longtime critic of such offices and the author of "Quiet: The Power of Introverts," says change is afoot. Companies are slowly beginning to realize that open-office designs, while helpful in encouraging collaboration, can also alienate employees.

"Solitude is a crucial ingredient of productivity, and one we want to bring back to the workplace," she said at the TED conference here Thursday, while announcing her own efforts to better design offices for introverts. "It takes a while for changes in sentiment to be reflected in architecture, but people are increasingly receptive to these ideas."

For Cain, an expert on introversion, such a shift has been years in the making. She started researching open offices in the mid-2000s when she made a trip to Silicon Valley, saw rows of desks with little privacy and found them to be "ridiculous."

As she noted in the New York Times years later, individual work had disappeared -- not just at tech companies, but in the broader culture. "Most of us now work in teams, in offices without walls, for managers who prize people skills above all," she wrote. "Lone geniuses are out. Collaboration is in."

About 70 percent of offices now have open layouts, according to a facilities trade group. Companies tend to like the plans because they take up less space than individual offices, reduce real estate costs and make it easier for employees to talk to each other. But a growing body of research suggests they also add to workers' stress, make people more likely to get sick and lead to lower employee happiness.

"People are less productive, they can't focus, and paradoxically they make fewer friends, because the currency of friendship is sharing confidence," Cain told LinkedIn. "You can't do that when everyone is there."

Cain's focus on the benefits of quietness served as the basis for her wildly popular book,2012 TED talk (7 million views and rising), and, now, successful career as a defacto spokeswoman for introverts. She returned to TED this week as part of the conference's 30th anniversary, where she gave a short talk and laid out an extensive plan for the next phase of what she calls a "quiet revolution."

A leadership institute, to offer both online and in-person trainings, is in the works, as is a plan to help teachers better recognize the needs of introverted students who, for instance, may squirm at the thought of yet another group project. She's also working on creating a web-based video interview series with famous introverts, she told TED's blog.

But improving the office also remains the core of her plan.

Cain said Thursday she is working with furniture manufacturer Steelcase to design more quiet spaces into offices. The goal is to give workers more privacy, while still providing room to collaborate. Prototypes of the new layouts could be released later this year.

"The current open office plan as we know it, with no private spaces, that's going to beobsolete very quickly," she said.

But don't expect a return to cubicles, either, because Cain considers those "inherently dehumanizing." Instead, look for plans that give employees options.

"Do I want to be private right now, or do I want to be social? Introverts are going to more often choose private. But, for any individual, your tolerance or craving for solitude fluctuates throughout the day," she said. "Choice is going to be the new normal."