How do you pronounce the vowel in the article "the" when used before "evil"? (American English)
The general rule has [ði] before phonological vowel sounds, [ðə] before phonological consonant sounds. This is parallel to the use of "an" and "a". However, there are a few complications:
- [ði] is also used in some cases as an emphasized form of the definite article; this can occur no matter what sound the following word starts with.
- You might on occasion hear an English speaker say something more like [ðə] or [ðɪ] before a word that starts with a vowel rather than the standard [ði]. Apparently, the use of a non-standard reduced form like [ðə] is most likely before words that start with a stressed /i/ or /ɪ/ sound, such as "evil". Even in this case, though, the standard pronunciation is still the most common one and the one that I would recommend for an English language learner.
If you want to learn more details, the following linguistics article is where I got this information: Constraints on definite article alternation in speech production: To “thee” or not to “thee”? (by M. Gareth Gaskell , Helen Cox, Katherine Foley, Helen Grieve, Rachel O’Brien; Memory & Cognition July 2003, Volume 31, Issue 5, pp 715-727)