All languages have variations in pronunciation, usually based on regionalism.  There are those who strive to erase such dialects from their language in order to “fit in” better, or to appear more cultured or educated. An opposing school of thought would like to see the use of dialects encouraged, since they reflect the traditions and history of an area and are threatened with extinction  by mass media.  Sites are popping up on the internet that request speakers of native regional accents to record their voices, in fear that this piece of history will soon be lost forever. Even English, the most media conscious of languages has versions almost so different in some countries as to be almost a different language. This, in countries where it is the official language such Australia, Canada, England, Ireland, South Africa and the United States.

In most instances, differing dialects can be understood by native speakers of that languge.
Where a problem frequently arises, however is how well non-native speakers can understand.  “Received pronunciation”, is the English associated with the educated classes of Britain in the past and with the royal family. It is sometimes called BBC English and is the English that has been taught in commonwealth countries such as India.  It is frequently also the standard pronunciation for English language courses taught in non-English speaking countries.  A Brit may have little to no trouble understanding an
American from Chicago or Boston, despite their differing “a”s.  A Swiss, Frenchman or German however, who learned “proper” English pronunciation in school may become quickly confused when trying to understand the many variations of American English.  

The same phenomenon can occur in other languages.  A Frenchman will have no problem understanding the vagaries of Canadian  French, but the American who studied Parisian French at the Berlitz school will have quite a time picking his way through a conversation with a Montrealer.

(This combination gets very interesting and more challenging when a non-native speaker communicates with another non-native speaker in a common language.  Take, for instance, our Berlitz trained American trying to order in French from a Turkish waiter who learned French at his local school!)

Should regional dialects be encouraged or discouraged?  Society has and continues to form unwritten rules that dictate how we behave.  A New Yorker with a strong “dese and dose” accent may work very hard to suppress it if he feels it stands in the way of a successful career. On the other hand, a New York cabbie may be proud of his accent and feel it will serve as a reflection of his knowledge of the city.  Many southerners try to change their accent to avoid sounding like “hicks”, but there are many who are proud of the lilting tones and gentle expressions of the southern belle.