In the often loud and frequently inane blah-blah-blah that is radio, Milt Rosenberg was for nearly half a century an oasis of intelligent conversation and learned curiosity.

Ever mindful of the intelligence of his listeners, Rosenberg was a late-night radio fixture who interviewed an astonishing array of guests from all walks of life — among the eclectic hundreds were Henry Kissinger, Carl Sagan, Jimmy Carter, Norman Mailer, Bob Feller, Bill Murray, Jane Byrne and Barack Obama — and actively engaged with listeners, sometimes contentiously, on his late-night “Extension 720” program on WGN-AM 720.

The late John Callaway of WTTW-Ch. 11, no slouch himself at the interviewing game, once said, “When Milt Rosenberg formulates a question with a premise in which he refers in two different languages to four different books, I say to myself, ‘That's smart. That's big-time smart.’”

Rosenberg died of pneumonia and its complications Tuesday. He had entered the hospital in Chicago on New Year’s Day. He was 92, his death announced by his friend Joe Morris.

Milton J. Rosenberg was born in New York City on April 15, 1925. An academic in heart and mind, he earned an undergraduate degree at Brooklyn College, a master’s from the University of Wisconsin and a Ph.D. in psychology at the University of Michigan. He taught at Yale University, Ohio State University, Dartmouth College and the Naval War College before arriving at the University of Chicago in the mid-1960s, where he would remain as director of the doctoral program in social and organizational psychology and eventually become a professor emeritus.

“Extension 720” was already a WGN offering when Rosenberg was hired to be one of a revolving cast of hosts. An occasional guest on that program, he had scant other on-air experience, his radio work to that point consisting of moderating recorded conversations between faculty members and visitors to the U. of C. campus. One of those 30-minute-long tapes was mailed to more than 100 stations across the country to be used free of charge.

When he was offered the job of solo host on “Extension 720” in 1973, he was not particularly confident, saying, “I thought I'd do it for a year or two — to buy a new car.”

But he had a longer run. “He is the Lou Gehrig of intellectual talk radio,” Joseph Epstein, the essayist and occasional guest on the show, said in 2008, when Rosenberg was awarded a National Humanities Medal, which cited him for “bringing the world of ideas to millions of listeners.” “During a single week he can do shows about financial markets, American musical theater, the state of contemporary academic life, nuclear warfare and the modern novel,” Epstein said. “It’s amazing, really."

The two-hour daily weeknight broadcasts (sometimes pre-empted by baseball or hockey games) featured an hourlong interview with his guests followed by an hour during which listeners could share by telephone their opinions, gripes and questions.

He selected his guests carefully, once telling a Tribune reporter, “I’m very particular about the authors I put on the air. If I don’t like the book, I don’t interview the author.”

A frequent guest over the decades was Tribune writer Ron Grossman, who said, “He had an enormous fund of knowledge, beyond his social-psychologist base. That’s the reason callers would begin by saying, ‘Good evening, Dr. Rosenberg.’

“More than once, I was the victim of his erudition. Once I quoted an early Christian theologian: “Credo quia absurdum” (“I believe because it doesn’t make sense”). Milt named the guy who actually said it and what the guy I was referring to actually had said. I’ll miss him.”

For all of his admirers — Steve Allen once said, “All interviewers should be forced to attend a class in that particular art, conducted by Milt Rosenberg” — Rosenberg also had detractors, people who felt that his intelligence could often come off as arrogance and his manner as haughty or dismissive.

And there were many who felt that Rosenberg’s personal political views, leaning increasingly to the right, began to creep more forcefully and, for some, alarmingly into his program.

Still, some of those closest to him saw a side the listeners never did. Stephanie Menendez, now WGN’s director of news and operations, worked as Rosenberg’s producer for a year around 2010. (To even be considered for such a job, applicants had to correctly answer a legendarily difficult series of questions posed by Rosenberg).

“I think most people remember Milt as a genius, and he was,” she said. “But when I think about him I remember our gossip sessions, giggles about goofs and goof-ups at the station. When I was working with Milt, he made me feel as smart as he was. He bounced ideas off of me. He was smarter than anyone I had ever met, but he made me feel like his equal.”

In 2012, as new management took over the station, Rosenberg was forced to retire. (There are a couple of shows available at www.wgnradio.com). “They are not the smartest people in the building,” he told a friend at the time, and then he embarked on producing a podcast featuring many of his previous interviews.

And in 2014 he was among the inaugural inductees into the WGN Radio Walk of Fame, with a plaque installed in the sidewalk outside Tribune Tower. Still lively and curious, he continued his independent podcast and later was heard for a time on WCGO-AM 1590.

Rosenberg is survived by his wife of more than 64 years, Marjorie Anne King, their son Matthew Rosenberg and two grandchildren.

Services are pending.

rkogan@chicagotribune.com

Twitter @rickkogan

From 2012: Milt Rosenberg retires after 39 years at WGN »

From 2014: WGN Radio honors its stars: Legendary personalities given markers in Walk of Fame »

From 2012: Milt Rosenberg's remarkable 'Extension 720' comes to an end »