WASHINGTON, DC - JUNE 18: View out the window during a media tour of the new NPR headquarters, 1111 North Capitol Street NE, Washington, DC, June 18, 2013. (Photo by Evy Mages/For The Washington Post) (Evy Mages/FOR THE WASHINGTON POST)

It’s a question sometimes whispered but never boldly confronted: Does NPR, and public radio in general, sound too “white”?

NPR itself suggested Thursday that the answer might be yes in an unusual bit of public self-examination. In a commentary aired on “All Things Considered,” its signature newscast, and in a subsequent Twitter chat that quickly trended nationally, the public radio network lit the fuse on an explosive discussion about how a broadcast should sound.

The commentary came from Chenjerai Kumanyika, an African American who is an assistant professor of communication studies at Clemson University and a radio producer. Kumanyika’s “All Things Considered” piece left no doubt about his point of view: It was titled “Challenging the Whiteness of Public Radio.”

While editing a script aloud for another public radio program last June, Kumanyika said in his commentary, he realized he was “imagining another voice, one that sounded more white.”

As a result, he concluded: “Without being directly told, people like me learn that our way of speaking isn’t professional. And you start to imitate the standard or even hide the distinctive features of your own voice. This is one of the reasons that some of my black and brown friends refuse to listen to some of my favorite radio shows despite my most passionate efforts.”

The NPR headquarters are located in NE Washington. (Evy Mages/For The Washington Post)

Kumanyika was referring to the subtle matter of code-switching, or speaking one way to one’s immediate peers and another way — call it more “white” — to a larger group. No matter the racial or ethnic identity of the speaker, people on public radio sound white, he suggested.

“I was hoping to expand the conversation,” Kumanyika said in an interview. “This is not only about race but about class and ethnicity, too. I was hoping that audiences and listeners can begin to rethink what their expectations are and what we’re missing if we don’t challenge our comfort zones.”

The topic immediately blew up on Twitter, drawing thousands of comments in a long-running “tweetup” (at #PubRadioVoice) hosted by several of NPR’s African American and Latino journalists, including Audie Cornish, a host of “All Things Considered.”

“What is ‘professional’?” tweeted Stacey E. Singleton, a lawyer. “So many deeply embedded layers of what people presume educated/professional is supposed to sound like.”

“You know how [Kumanyika’s] friend doesn’t like Pub Radio because it doesn’t sound like him? White people would go the same way,” wrote Andy Wardlaw, an editor.

Lizzie O’Leary, who hosts public radio’s “Marketplace Weekend,” tweeted that women can also face an issue on the air: “I was excited about something and a listener complained I sounded ‘like a sorority girl.’ ’’

Like many news organizations, Washington-based NPR has long struggled with diversity, on and off the air. Most infamously, it drew an avalanche of criticism in 2010 when it dismissed news analyst Juan Williams — its only African American commentator — after he made some intemperate remarks on a Fox News program. It also drew grief last year when it dropped “Tell Me More,” a daily news-discussion program designed to increase NPR’s minority audience.

Amid those episodes, NPR started Code Switch, with a team of journalists covering race and culture, both online and on the air. The unit organized the Twitter discussion about public radio voices.

The Twitter response is “an indicator of how much people wanted to have this conversation,” said Lynette Clemetson, who heads the 11-member Identity and Culture reporting unit at NPR that includes Code Switch.

The generally middle American — i.e., “white” — sound of NPR is perhaps most evident, even startling, when reporters of Latino heritage “sign” their reports by saying their names with a strongly Spanish pronunciation. Sylvia Poggioli, NPR’s longtime correspondent in Rome, is perhaps as famous for her reporting as for the distinctive way she pronounces her name with an Italian inflection.

At its most hilarious, the NPR “sound” was captured by “Saturday Night Live” several years ago in a serial skit about a fictitious public radio cooking show, “Delicious Dish.” Cast members Ana Gasteyer and Molly Shannon as the hosts, and Alec Baldwin as a frequent guest, captured the cooing, lulling, almost hypnotic slow-rolling rhythms of an NPR broadcast.

“We really have to think about who is the public in ‘public media,’ ” Kumanyika said in his “All Things Considered” commentary. “The demographics of race and ethnicity are changing in the United States. The sound of public media must reflect that diversity. So get on it. It’s time to make moves.”