There's a great story making the rounds. According to Joe Fay ("Czech falls off motorbike, wakes up with British accent", The Register, 9/14/2004):
A Czech speedway racer discovered his inner British toff after another rider ran over his head.
Non-English speaker Matej Kus, 18, took the spill during a race in the UK. Paramedics were stunned when he came round and asked where he was – in perfect English. It soon became apparent that Kus had lost his memory, forgetting he was a Czech bike racer, and presumably thinking he was an accent coach at the BBC.
Team manager Peter Waite told Ananova that Kus sounded “like a newsreader”. The biker's foray into the world of received pronunciation was shortlived, however. As soon as his memory returned, two days later, his command of English evaporated.
Speaking through an interpreter, Kus said: "There must be some English deep in my head…Hopefully I can pick some English up so I'll be able to speak it without someone having to hit me over the head." [...]
Doctors put the baffling linguistic transformation down to Foreign Accent Syndrome, a rare condition where a blow to the head – or a stroke – damages the parts of the brain that control speech.
In 2004 a Bristol woman woke up speaking French and thinking she was living in Paris. She was subsequently diagnosed with Susac’s syndrome. As she explained to the Daily Mail last year, "It might sound funny to others, but suddenly thinking you are French is terrifying."
The headline writers have had a lot of fun with this one -- The Register's sub-head was "Bohemian rhapsodises in cut-glass English". Ananova's story ran as "Czech out the new lingo".
Matej repeated for the Daily Mail the standard folk-scientific story about this sort of thing:
After flying home to the Czech Republic to recover, he said - through an interpreter - that he remembered nothing of the accident or of the following two days.
Yesterday he added: "It's unbelievable that I was speaking English like that, especially without an accent. "Hopefully I can pick English up over the winter for the start of next season so I'll be able to speak it without someone having to hit me over the head first.
"There must be plenty of the English language in my subconscious so hopefully I'll be able to pick it up quickly next time."
I'll keep an open mind about this -- perhaps during the two days that Matej allegedly spoke perfect BBC-newsreader English, someone thought to tape some of it. But pending some evidence more credible than reported interview statements by the team manager, I'm agreeing with the doctors who put this down to Foreign Accent Syndrome, in which head injury cause someone to talk funny, and casual observers dream up various alternative specific but fanciful interpretations. The wikipedia article notes a FAS case that was documented on the air in 2006 (by the BBC):
Another case of foreign accent syndrome occurred to Linda Walker, a 60 year old woman from the Newcastle area. After a stroke, her normal Geordie accent was transformed and has been variously described as resembling a Jamaican, as well as a French Canadian, and a Slovak accent. She was interviewed by BBC News 24  and appeared on the Richard and Judy show in the UK in July 2006 to speak of her ordeal.
I'll also note that this is a case of life imitating the funny papers -- see "Memetic mutation and traumatic release", 8/30/2007.
This traumatic xenoglossy stuff is also more peripherally connected to the phenomena of "speaking in tongues", and to the cases of alleged recovery of past-life languages through hypnotic regression (see S. Thomason, "Do you remember your previous life's language in your present incarnation" American Speech, 59:340-350. 1984).
[So far, I haven't found any links to careful studies of cases where a head injury is said to have created the ability to speak a language that the victim did not previously know. But there are plenty of careful studies of FAS, for instance these:
Sheila Blumstein et al., "On the nature of foreign accent syndrome: a case study", Brain and Language, 31(2):215-44, 1987. The abstract:
A detailed acoustic analysis was conducted of the speech production of a single patient presenting with the foreign accent syndrome subsequent to a left-hemisphere stroke in the subcortical white matter of the pre-rolandic and post-rolandic gyri at the level of the body of the lateral ventricle. It was the object of this research to determine those changes which contribute to the perception of a “foreign accent.” A number of acoustic parameters were investigated, including features of consonant production relating to voice, place, and manner of articulation, vowel production relating to vowel quality and duration, and speech melody relating to fundamental frequency. The results indicated that many attributes which might have contributed to the foreign quality of the patient's speech were similar to those of normal English speakers. However, a number of critical elements involving consonant and vowel production and intonation were impaired. It was hypothesized that the acoustically anomalous features are linked to a common underlying deficit relating to speech prosody. It is suggested that the normal listener categorizes this speech pattern as a foreign accent because the anomalous speech characteristics, while not a part of the English phonetic inventory, reflect stereotypical features which are a part of the universal phonetic properties found in natural language.
Kathleen M. Kurowski et al., "The foreign accent syndrome: a reconsideration", Brain and Language, 54(1):1-25, 1996. The abstract:
This study compared the post-CVA speech of a patient presenting with the foreign accent syndrome (FAS) to both a premorbid baseline for that patient and to similarly analyzed data from an earlier reported case of FAS. The object of this research was to provide quantitative acoustic data to determine whether: (1) the constellation of phonetic features associated with FAS is the same across patients and (2) a common neural mechanism underlies FAS. Acoustic parameters investigated included features of consonant production (voicing, place and manner of articulation), vowel production (formant frequency and duration), and prosody. Results supported the characterization of FAS patients as having a “generic” foreign accent and the hypothesis that FAS deficits are qualitatively different from that of Broca's aphasia. However, comparison of this case with recent studies revealed the extent to which the constellation of phonetic features may vary among FAS patients, challenging the notion that a general prosodic disturbance is the sole underlying mechanism in FAS.
Inger Moen, "Foreign accent syndrome: A review of contemporary explanations", Aphasiology 14(1):5-15, 2000. The abstract:
This paper presents an overview of the cases of the so-called foreign accent syndrome (FAS) which have appeared in the literature during the last ten to fifteen years and discusses the explanations that have been offered to account for the anomalous phonetic/phonological features of the patients speech. Explanations for the underlying nature of the production disorder in FAS have been given in terms of phonetic setting, in terms of mechanisms for the control of speech motor behaviour, in terms of cognitive processing and in terms of phonological theory. FAS can be seen as an apraxic condition where the ability to control and coordinate the various laryngeal and supralaryngeal features of speech has been damaged. Recent developments in phonological theory, models where the distinction between a phonetic and a phonological level of analysis is less clear cut than in most models, offer interesting perspectives on the description and analysis of FAS.
Lila Guterman, "When Speech Goes Strange", Chronicle of Higher Education, 11/15/2002
Jo Verhoevan and Peter Marien, "Prosody and Foreign Accent Syndrome: a Comparison of Pre- and Post-stroke Speech", Speech Prosody 2004.
Diane Garst et al., "Foreign Accent Syndrome", The ASHA Leader, 11(10):10-11, 2006.
]Posted by Mark Liberman at September 16, 2007 08:19 AM