How do different accents of the same language come about such as American and Australian?

Answer 1

Accents are influenced by geographic separation, cultural influence, and other languages from closest geographic regions. Think about the way American Southerners speak in Tennessee vs. Louisiana. In Louisiana the accent is very French influenced. When the English colonised Australia it was as a place to exile thieves and other criminals. Typically, the thieves and criminals were of the lower class and therefore spoke an uneducated version of English with a lot of slang and its own idiom. Over a couple of hundred years, the language evolved into what you know of as the Australian accent. Listen to a Cockney street accent and then an Australian accent and you should hear the similarities.

A lot of the convicts sent to the Australian colonies were Irish (eg Fenians) and their accent and idiom have influenced the present Australian accent. Additionally, much Australian idiom resulted from both naval terms, and from raising sheep (the main industry of the young nation) in addition to the argot many convicts learned on prison hulks before they left Britain.

Non-native speakers of English have accents which are influenced by their native tongue, hence one can tell a Russian from an Indian, both speaking English. Some languages may lack a particular sound, for instance the two ways of pronouncing "th" in English and so non-native speakers struggle with words containing those sounds.

Regional accents in England itself arose in part because Old English had several major dialects, and the Modern English reflects, in many ways, those regional differences. One example is the sounds of the words for the same species, namely "fox" and "vixen", which came from different Old English dialects.

The preponderence of convicts from the London area, and also Ireland, in part make for the unique Australian accent, just as the preponderence of Scottish immigrants explains the "burr" in the speech of many New Zealanders from the southern part of the South Island.