Even as millions tune in to the next round of auditions on “American Idol,” they aren’t likely to forget Lazaro Arbos, one of last week’s stand-out contestants whose voice visibly stunned the judges.

Arbos stuttered while introducing himself and the song he was set to sing, but once he broke into “Bridge Over Troubled Waters,” the stammering was gone. The performance won him four “yes” votes from the panel and a spot in the next round in Hollywood. 

But it also left many people wondering why a person may stutter while speaking but not while singing. 

Speech pathologists say there is not yet a scientifically proven answer to that question, but there are likely a number of physiologic, genetic, environmental and social variables that play a role.

One plausible explanation, said Krzysztof Izdebski, chairman of the Pacific Voice and Speech Foundation in San Francisco, is that singing relies mostly on memory.

“When you speak, on the other hand, it’s more of a voluntary activity. There’s planning, thinking, reaction, et cetera. Singing requires different mechanisms,” he said. People who stutter may be unable to coordinate all the movements and processes involved in speech, he explained.

“The more automatic the speech is, the less someone is likely to stutter,” added Karin Wexler, an adjunct associate professor of speech and language pathology at Columbia University’s Teachers College in New York.  “The same goes for reciting a poem.  There’s no real communication involved.”

After the stirring performance, “Idol” judges Keith Urban and Randy Jackson told Arbos that he should just “sing all the time.” But according to the Stuttering Project at the University of Iowa, while people who stutter may be able to sing stutter-free, singing will “rarely produce long-term fluency.”

Wexler also explained that speaking requires the voice box to work a lot more because there is repeated starting and stopping, unlike singing, which is a more continuous flow. 

“Getting the voice started can be a problem for someone who stutters,” she said. 

The enigmatic phenomenon could also be due to the differences in brain activity elicited by singing and speaking. Each is associated with a different part of the brain, and perhaps the musical signals get routed differently, according to Izdebski.

And it’s not just stammering that gets lost when some people break into song. Accents tend to disappear as well.

“Singing is never spontaneous.  People learn a song and will sing it as they heard it,” said Izdebski. 

In fact, speaking with a different accent actually seems to help some stutterers.

“If they are speaking in a different way from their ordinary way of speaking, they may become more fluent,” said Wexler.   

It’s too early to tell whether Arbos will win it all, but the Stuttering Foundation of America already considers him an American idol.

Said the foundation in a press release, “For his courage to speak and perform on one of the most-watched shows on television in America, Lazaro Arbos is already a winner to the stuttering community.” 

Related:

Singer silences his stutter with song on 'American Idol'

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It seems stammering is having a moment: Early this morning, "The King's Speech" received 12 Academy Award nominations, more than any other film this year. One of those nods went to Colin Firth, who many expect to win for his portrayal of King George VI, the English king with a debilitating stammer. Now the speech impediment is all the Internet can talk about.

But one type of stammer that's not being widely discussed is sudden onset stuttering. For most, stuttering begins in childhood, while children are developing language skills – but in rare cases, it can come come on suddenly, mangling the speech of adults who'd never struggled with the problem before.

The cause of sudden onset stuttering is either neurogenic (meaning the brain has trouble sending signals to nerves, muscles or areas of the brain that control speaking) or psychogenic (caused by emotional problems). A sudden stutter can be caused by a number of things: brain trauma, epilepsy, drug abuse (particularly heroin), chronic depression or even attempted suicide using barbiturates, according to the National Institutes of Health.

In sudden cases sparked by underlying psychological issues, "often times, you can find that it's not so sudden; there might be a history of stuttering that had been outgrown," says Dr. Tommie L. Robinson, former president of American Speech-Language-Hearing Association and director of the speech and hearing program at Children’s Nation Medical Center in Washington, D.C.

According to one 1998 case report, a 30-year-old woman hit her head in a car crash, and the trauma to her brain appeared to cause a temporary stutter.  And in a 1982 case, a 28-year-old man developed a stutter after a suicide attempt; his doctors believe his sudden speech impediment was the result of psychological distress.

The movie hints that the king’s trouble with speech may have been psychogenic, as it may have been the result of the extreme pressure he felt from his father. (When he begins to have trouble getting out the words, his father demands, “Get it out, boy!” Not exactly helpful.) Experts once believed all cases of stuttering were psychogenic, but that particular cause is actually known to be very rare. In fact, last year scientists isolated three genes that cause stuttering.

Oh, and in case you were wondering: stuttering and stammering are synonymous, Robinson says. "'Stammering' is more of a British thing," he explains.

Some quick facts on stuttering from the National Institute on Deafness and Other Communication Disorders:

• Stuttering affects people of all ages, but it most often begins in children ages 2 to 5, as they develop language skills.
• About 5 percent of all children stutter at some point in their life.
• Boys are twice as likely to stutter as girls – and as they grow up, the number of boys who continue to stutter is three to four times larger than the number of girls.
• Most children grow out of their stutter. Only about 1 percent of adults stutter.

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