In the video, Hillary Clinton sounds sympathetic. She also sounds — Southern?

"Mah gosh," the Chicago-born Democratic presidential frontrunner says, sliding into a down-home drawl while describing a college student's debt.

Polling the Alabama crowd, she asks whether anyone has a "hah-yer" interest rate.

Clinton's speech was days before she would rebound in South Carolina after losing in New Hampshire. But sharp-eared conservative politicos were hearing hints of another comeback: the return of "Southern Hillary."

Listen to Clinton's speaking styles:

Hillary Clinton speaking style0:25

Sociolinguists call it code-switching — an everyday toggling between languages, dialects or speaking styles, typically an automatic practice.

We all do it, says Georgetown University linguistics professor Deborah Tannen.

But it seems to be even more apparent during a U.S. presidential campaign, particularly when stumping means criss-crossing a country as regionally and dialectically diverse as America.

Speech experts, however, say it's not as simple as chalking it up to pandering.

"I've noticed it over the years. Not just in this campaign, but in all of them," Tannen says. "When it's done by a politician, the assumption tends to be that it's somewhat nefarious or manipulative. The truth is, it's instinctive accommodation, or a sign of acceptance."

Feelin' folksy

In other words, when so much about campaigning is about connecting with audiences, a little mirroring of speech patterns sometimes slips in.

Before he dropped out of the Republican race, Wisconsin Gov. Scott Walker caught flack for losing his natural Midwestern accent and affecting a more general-election speaking style.

Walker's northern cities vowel shift (as the linguists call it), in which "A" sounds replace "O" sounds — like, "e-cannamy" for economy — morphed into a standard American-English accent while he was trying to look presidential.

Listen to Walker's speaking styles:

Scott Walker speaking style0:22

That's not to say a broader accent necessarily holds the broadest appeal.

"The general thing people say about regional dialects is it makes people sound like just regular folks," Tannen says. "People like it because it feels homey."

Take, for example, the divergences between one-time Republican hopeful Jeb Bush and his older brother, former president George W. Bush.

"Jeb didn't come across as as folksy as his brother did," says Walt Wolfram, a North Carolina State University linguistics professor who has analyzed presidential speech patterns for such Southernisms as "y'all" and "I'm fixin' to."

Despite growing up in the same household, Dubya picked up a Texas twang.

The difference is also clear in the way they use personal pronouns, with Jeb cultivating a more uppity, standard-English accent ("I pledge to you") versus his brother's ("Ah applaud yur gov'nor") during campaigning last month.

"Jeb Bush came across as more blandly standard. And maybe that was one of his problems," Wolfram says, referring to the Florida governor's failed nomination bid.

Listen to clips of Jeb Bush and George W. Bush:

Jeb and George W. Bush speaking styles0:24

Preacher man

Code-switching applies not only to accents, but also varieties of speech.

In Ted Cruz's case, for example, stump speeches can sound like megachurch sermons.

The Republican presidential candidate often uses a preacher-like tone, alternating between soaring and hushed pitches, and filling in phrases with dramatic pauses, particularly when addressing largely evangelical crowds.

Dennis Goldford, a politics professor at Iowa's Drake University, noticed it when Cruz was campaigning during the Iowa caucuses.

"He will space between his words, and his sentences, and make you pay closer attention," Goldford says. "It's a real tic. There's a sense of performance there."

Michael Newman, a linguist with Queens College at the City University of New York, says that whether it's conscious or not, Cruz appears to be "indexing Christian ministry" to appeal to conservatives.

Listen to Ted Cruz's speaking styles:

Ted Cruz speaking style0:22

"He has to sound 'Christian', so he's playing to a different set of values," Newman says.

The New Yorkers

Two candidates who have not noticeably shifted their linguistic styles are the New Yorkers.

Bernie Sanders, Clinton's Brooklyn-accented rival for the Democratic nomination, continues to speak with a "non-rhotic accent," dropping R sounds after vowels. It's why New York becomes New "Yawk."

Sanders has not changed it up. ("We aww gaining momentum!" he said at a South Carolina rally last month.)

Listen to Sanders's non-rhotic accent:

Bernie Sanders speaking style0:21

Nor has Republican frontrunner Donald Trump strayed from his Queens habit of weakening the initial H sound in words like "human" and "hue", the trait that gave the internet the "yuuuge" meme.

Newman believes the two native New Yorkers, both of whom have scored points for authenticity, are having their brands reinforced by "a social identity that sounds like toughness, and comes through in their accents."

"Bernie and Trump, for all the differences in substance between them, their New York accents are helping them," he said. "That accent is associated with saying what you mean, and with not beating around the bush. It sounds working class."

On at least that point, former Democratic campaign consultant Bob Shrum found himself agreeing.

Listen to Trump's non-rhotic accent:

Donald Trump speaking style0:12

"Trump has a quintessential New York accent," said Shrum, who previously served as a senior adviser to John Kerry and Al Gore.

"Look, he sounds authentic," he said. "I think he's an authentic demagogue."

But Shrum also says that as much as Clinton's right-wing opponents mocked her switched-on drawl as contrived, it probably wasn't.

"She lived down in Arkansas for a long time. She just slipped into it," he says.

"Cruz does it occasionally, too. He slips into this kind of more Texas thing, more Texas than he usually is, but that's kind of natural. That probably would be the first thing I'd ever defended Ted Cruz about."

During his time working with Gore, Shrum said the former vice-president had a soft Tennessee lilt that would occasionally come out in conversations. Kerry's accent was flat.

President Barack Obama has shown a facility for code-switching when he meets with black and white voters, once declining a black cashier's fistful of change at a D.C. chili restaurant with, "Nah, we straight."

Listen to an example of Obama's code-switching:

Barack Obama speaking style0:18

The perception of a candidate slipping in and out of speaking styles can seem disingenuous.

Even if candidates aren't conscious of it, Shrum says, "you're going to get accused of changing yourself to appeal to a particular audience, and that can only hurt you."

Previous presidents with strong regional accents included Georgian Jimmy Carter, proud Missourian Harry Truman and Massachusetts-born John F. Kennedy.

The gain any candidate gets from an accent is speculative, though. What it comes down to, according to Shrum, is relatability.

"The advice is just to speak like you always speak," Shrum says. If you wanted to be like Bill Clinton, you can speak with a Southern accent. "But if you didn't have Clinton's warmth and ability to connect, what did it matter?"