In particular, the vowel of the last syllable was a pretty good IPA [e], not diphthongized like the vowel in English babe but also not laxed and shortened like the vowel in English bed.
What is more, he observes that the diphthongisation works more efficiently when the word in question is feminine, and less systematically when the word is masculine or higher register.
Our interest here is in whether Spanish speakers go beyond this, internalizing rich and detailed knowledge of the ways in which diphthongization is conditioned by the segmental environments.
Stealth has a long, tense, diphthongized high vowel [i], whereas stealth has a short, lax, mid-vowel.
But at normal conversational speed its ghastly sequence of four diphthongized long vowels (in the nicely symmetrical but un-IPA Trager-Smith transcription, / ay ey iy ey /) sounds something like ah-ee-yay-ee-yee-yay-ee.
Nonetheless, a number of studies suggest that at least diphthongization and nasal and lateral depalatalization may be unproductive in Spanish.
This conlang is based on High Latin and derives its words from the latter by some rather original phonological processes, including diphthongisation and initial mutation.
The diphthongisation of [i:] and [y:] led to a merging of sounds as can be seen in this table.