Imagine being involved in a nasty car crash, and waking up in hospital to find yourself talking with a foreign-sounding accent.
That is exactly what happened to Tasmanian woman Leanne Rowe, who has been speaking with a "French" accent after suffering a head injury in a crash eight years ago.
Then there is the case of a 13-year-old Australian boy, who developed an "American" accent after being involved in a serious traffic smash.
His baffled parents said his accent persisted for about five months after the crash, before disappearing overnight after the teenager watched Crocodile Dundee.
Both patients are among only about 70 documented people worldwide who suffer from Foreign Accent Syndrome, a rare disorder in which the speech area of the brain is slightly damaged.
Dr Karen Croot, a lecturer in applied cognitive psychology at the University of Sydney, has studied the syndrome and said it affected the very late processes in talking, including the position a person put their mouth and larynx to produce sound.
"It's all about the positioning of the speech articulators and about the tension. When we talk normally those things are controlled by a network of centres in the brain, and it's incredibly precise," she said.
Dr Kroot said in patients with Foreign Accent Syndrome, a part of that speech network in the brain was damaged slightly, and their new patterns of speech overlapped with features of a known accent.
"The person is still able to coordinate very clearly what it is that they want to say, it's just like it has been tweaked differently," Dr Croot said.
"It has a different setting, and it happens that that setting overlaps with the setting that's used by some speakers from other languages."
Ms Rowe told the ABC that she woke up in Melbourne's Austin Hospital with a broken back and jaw after being involved in a serious car accident.
"Slowly, as my jaw started to heal, they said that I was slurring my words because I was on very powerful tablets," she said.
But the accent remained, and she is facing the prospect of speaking with a "French" accent for life.
"It makes me so angry because I am Australian," Ms Rowe said of her accent.
"I am not French, [though] I do not have anything against the French people."
The former bus driver and Army Reserves member told the ABC she had developed anxiety and depression because of her accent, and had become a recluse.
Dr Kroot said a native French speaker or a linguist might not think that an accent such as Ms Rowe's sounded French, but most non-French speakers tuned their ears to the accent that they were used to.
But a person's accent did affect their feelings of belonging and their identity, Dr Kroot said.
The first documented case of Foreign Accent Syndrome was in Norway during World War II, when a 28-year-old woman was struck in the head by a piece of shrapnel.
She was unconscious for several days, before waking to speak with a German-like accent, which led to problems for her during the war.
Last year, British singer George Michael revealed that, following a near-fatal bout of pneumonia, he woke from a coma to talk temporarily with what sounded like a broad West Country accent spoken in western England.
"There's nothing wrong with a West Country accent," said the former star of the 1980s pop duo Wham!, "but it's a bit weird when you're from north London.
"My sisters, who were obviously so relieved that I'd actually woken up, were just laughing away at this stand-up comedy."
In 2010, Kay Russell, 49, from Gloucestershire in England, woke from an afternoon nap to find her clipped English accent had been replaced by more of a Gallic lilt.
She had endured a series of hemiplegic migraines that caused minor brain damage.
The same year, British woman Sarah Colwill suddenly started speaking with a "Chinese" accent after suffering a severe migraine.
Her distinctive West Country drawl was replaced with a Chinese twang, even though she had never visited the country.
- FFX Aus
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