Impersonating accents convincingly seems to take some kind of natural talent. While Meryl Streep's boundless ability allows her to mimic the speech patterns of pretty much any variety of spoken English, the average American's repertoire probably consists of painfully lame single-phrase attempts at different accents — "'ello gov'na!" or "pahk the cah in Hahvahd Yahd."

According to a new imaging study, specific regions of the brain are called into play by such attempts to alter one's voice.

"The voice is a powerful channel for the expression of our identity — it conveys information such as gender, age and place of birth, but crucially, it also expresses who we want to be," said lead author Carolyn McGettigan of University College London.

Along with a team of British and Dutch researchers, McGettigan decided to explore how the brain modulates among different modes of speaking.

Impersonating Voices During Brain Scans

Previous research has found that hearing voices activates parts of the brain's temporal lobe, but no previous studies had investigated which regions control vocal shifts.

"Consider the difference between talking to a friend on the phone, talking to a police officer who's cautioning you for parking violation, or speaking to a young infant," she said.

Your tone of voice is likely to shift in ways that are specific to each situation, McGettigan suggests. Just as close friends would find it off-putting if you suddenly spoke to them in a clipped, subservient tone, a police officer would be unlikely to respond well to baby talk.

The researchers investigated the neural basis of vocal impersonations with functional magnetic resonance imaging (fMRI) scanning.

Twenty-three adult English speakers (undoubtedly with a relatively high threshold for embarrassment) were asked to put together lists of 40 people and 40 accents that they expected to be able to impersonate.

The people they impersonated could be celebrities, like Sean Connery or Margaret Thatcher, or family members, friends, and acquaintances. The accents could be foreign or regional British ones.

In an fMRI scanner, the participants repeatedly recited a line from a familiar nursery rhyme, like "Jack and Jill went up the hill," in their normal voice, in impersonations of other individuals, or in impersonations of different accents.

While some of the participants had training in acting or music, none were professional vocal impressionists.

A Brain Network for Voice Impressions

The results showed that anytime participants intentionally changed their voices, the left anterior insula and left inferior frontal gyrus of their brains were activated — building on previous research suggesting that those regions are involved in the articulation of complex speech.

There were, however, particular differences between impersonations of individuals and of general accents.

Specific impersonations lit up areas in the right middle/anterior superior temporal sulcus and posterior superior temporal/inferior parietal cortex, but those regions showed comparatively lower response when participants emulated generic accents.

It's unclear why these particular brain regions are activated, but the researchers propose a general outline of how they work together to create shifts in speech production.

When a person impersonates someone else's voice, parts of the superior temporal lobe involved in the perception of other voices work with speech planning sites in the frontal cortex of the brain, they write. The right superior temporal cortex may be responsible for monitoring the voice for errors, so the impression sounds the way the impersonator wants it to sound.

In future studies, the researchers propose to repeat the same experiment with professional voice artists, who can help identify whether enhanced impersonation skills involve more specific functional brain networks.

Aside from allowing us to imagine how Meryl Streep's brain looks in an fMRI machine, this voice production research may have some practical value.

McGettigan suggests that it could ultimately lead to treatments for strokes and other brain injuries, which often lead to deficits in speech and language production like aphasias. Such therapies may be especially useful for a rare speech disorder called foreign accent syndrome, in which people can't help speaking in completely different accents after brain damage.

Source: McGettigan C, Eisner F, Agnew ZK, et al. T'ain't What You Say, It's the Way That You Say It-Left Insula and Inferior Frontal Cortex Work in Interaction with Superior Temporal Regions to Control the Performance of Vocal Impersonations. Journal of Cognitive Neuroscience. 2013.