Sometimes sounds should sound different but sound the same due to mispronunciation. Somekind of common standard of pronunciation helps people to be clearly understood by others, but there is no common standard which is imposed on all groups of native speakers. No single group has authority to claim that their standard is better, or even that they have the right to impose such a standard. Those who make claims about correct pronunciation often cite dictionaries as their authority
When we pronounce two distinct sounds in the same way so that the listener can not tell them apart, this is called a merger. The page looks at pairs of words which should sound different but which may become false homophones if the speaker merges these sounds into the same sound. Dictate each word pair to your teacher or partner and ask them to check your pronunciation by writing each word.