Thirty-five-year-old Sarah Colwill puts the startling change down to an extremely rare medical condition known as Foreign Accent Syndrome (FAS).
"I knew I sounded different but I didn't know how much and people said I sounded a bit Chinese.
"Then I had another attack and when the ambulance crew arrived they said I definitely sounded Chinese."
The rare disorder is thought to be caused by strokes and brain injuries and causes sufferers to lose the ability to talk in their native accent.
There have been an estimated 60 recorded cases of FAS since it was first identified in the 1940s.
Mrs Colwill, who lives in St Budeaux in Plymouth, Devon, with her husband Patrick said her accent change had been startling.
"I spoke to my stepdaughter on the phone from hospital and she didn't recognise who I was.
"She said I sounded Chinese. Since then I have had my friends hanging up on me because they think I'm a hoax caller."
After researching FAS on the internet Mrs Colwill has been in contact with doctors from Oxford University who are interested in studying her plight.
She is undergoing speech therapy to try to revert to her West Country accent.
"I am frustrated to sound like this. I just want my own voice back, but I don't know if I will get it back."
John Coleman, a professor of phonetics at Oxford University, said: "FAS is extremely diverse, almost certainly not 'one thing', not a well-defined medical phenomenon.
"It is not the kind of problem that there are any easy generalisations about."
Sufferers can develop an accent without ever having been exposed to it as it is the change in speech patterns from a brain injury which causes the lengthening of syllables, change in pitch or mispronunciation of sounds.
Experts believe FAS is triggered following a stroke or head injury, when tiny areas of the left side of the brain linked with language, pitch and speech patterns are damaged.
The result is often a drawing out or clipping of the vowels that mimic the accent of a particular country, even though the sufferer may have had limited exposure to that accent.
One of the first reported cases was in 1941 when a Norwegian woman developed a German accent after being hit by bomb shrapnel during an air raid.
As a result, she was shunned by her community, who falsely believed she was a German spy.
In 2006 Linda Walker, 60, woke from a stroke to find that her Geordie accent had been transformed into a Jamaican one.
