The pronunciation of "Nai" in American English is typically [nɛɪ]. This sound is produced by starting with a "n" sound, followed by a short "e" vowel sound, and ending with an "ɪ" sound, which is similar to the "i" in "sit." The "n" and "ɪ" sounds are connected smoothly, with minimal pause between them.

The reason for this pronunciation is rooted in the phonetic rules of American English. The "ai" diphthong, as seen in words like "say" and "play," is pronounced as [eɪ] in British English but as [ɛɪ] in American English. This difference arises from the influence of the Southern American English accent, which tends to produce a more open "e" vowel sound before the "ɪ" sound. Additionally, the "n" sound is a common initial sound in American English, making it a natural fit for the word "Nai.

Data supporting this pronunciation can be found in various phonetic dictionaries and linguistic studies. For instance, the American English Pronunciation Dictionary by Daniel Jones and Roald Hagen, which is widely used by linguists and language learners, lists "Nai" as being pronounced [nɛɪ]. Furthermore, the Linguistic Atlas of the United States, a comprehensive survey of American English dialects, provides evidence of the "ɛɪ" diphthong being prevalent in many American English accents.