The English of the southern USA is different from other regions of the country. It is a large area which includes Louisiana, Georgia and Tennessee. The accents are quite diverse. However, a number of features are characteristic of the region.
The diphthong of words such as my and tie is often realized as the monophthong of cat and sand. Other vowels such as those of sit, ate, pet, put and cat are pronounced as diphthongs. The second component of the diphthong is a schwa.
Before a nasal, the vowel of pen is raised and pronounced as the vowel of pin. As a result, the words pen and pin sound identical. The distinction is maintained before other sounds such as set and sit.
The words hoarse and horse are pronounced differently. The word hoarse has a diphthong. The first component is a mid back rounded tense vowel and the second is a schwa. In horse, the vowel is a monophthong. It is a mid back rounded lax vowel.
The English of the southern USA is different from other regions of the USA. It is spoken in a large area of the United States with a number of different accents. However, three features are universally true of this accent. They are the monophthongization of the vowel in pie, the diphthongization of vowels that are monophthongs in other regions, and the vowel raising that occurs before nasals.