original_query: What is a unique feature of Middle Atlantic speakers and southern New Englanders regarding vowel pronunciation?
query: What is a unique feature of Middle Atlantic speakers and southern New Englanders regarding vowel pronunciation?
answer: A unique feature is the raising and diphthongization of the vowel in words like 'out' to a higher position, often appearing as diphthongs with a centering glide. This makes them resistant to the cot-caught merger.