Pyles, Thomas and John Algeo, gave an example that the rule of pronouncing the letter "r". The concept of linking "r" which is used in British accent and it made difficult for the Americans to interpret certain words. This is a wide gap that made problem for the correspondence of the established and current English.
3. Elision: Due to less stress for words or letter the sound is omitted while pronouncing. As per Pyles, Thomas and John Algeo there are two types, in omitting the sounds either at the start or at the end of a word and it is called as aphesis and apocope respectively.
3. The History: The history of English language also is a cause for the diversity involved in the language. The English language is constructed from Greek and Latin. The people from different places took place in the event of the spreading of English language. And so there is a clear difference between the modern and established English.
4. Spellings and Pronunciation Variation: "The traditional words like bade are being transformed into bed" ( Pyles, Thomas and John Algeo, ch 3, pg 52). This is because of the adjustment made between the pronunciation and spelling. Hence pronunciation gap between the modern and traditional language.