Jimmy Wales wrote:
I talk to a lot of people who speak English with different sorts of accents, and it is very seldom a barrier to communication at all. It might be a bit surprising to listen to an English article read by Anthere, who speaks with a distinct French accent, but she's still very easy to understand.
This depends partly on where you're from, because if you change small bits, and then change small bits again, and so on, the overall difference gets quite large. Most people who speak English with a middle-of-the-road American or British accent are one degree away from most accents you'll encounter. A German who learns English, for example, almost always learns from a UK or US English role model---not from an Indian or Singaporean role model. So the Indian or Singaporean is two degrees of accents away from the German speaking English, while the American or Briton is only one degree away.
I know from personal experience that while most American students can understand nearly all the foreign-born professors I've had, albeit sometimes with some difficulty, many of the international students, even those who were born in English-speaking countries like India, have much more difficulty, especially with some of the European accents.
Although it smacks of a bit of accent imperialism, the most widely understood accents are probably some sort of middle-of-the-road American accent (i.e. not a strong New York, Southern, or Texas accent), and some sort of middle-of-the-road British accent (i.e. not Cockney). Of course, we could always provide multiple readings...
-Mark