There is no mystery to the Pronunciation of ‘a‘ and ‘the‘ in front of words! The ‘aye ‘ goes in front of vowels, ( aye uterus) however changes to ‘an’ when it is cumbersome (an octopus) . The ‘uh’ sound is used in front of consonants. Many people whose first language is not English or those with discreet dialects adopt incorrect usage feeling that it elevates their diction Now we have become accustomed to the nuance and linguists would accept it as correct for a region or culture. Listen to Rex Harrison in My Fair Lady singing Why Can’t The English (pronounced THEE ) Teach Their Children How To Speak?