diphthongize

vt.

双重元音化，发音成双重元音；

Old Spanish Resistance to Diphthongization, or Previous Vowel Lengthening?
Diphthongization as cue for the automatic identification of British English dialects
Perception of Diphthongized Vowels in Rhode Island English
Diphthongization and contrast realization in Huave
The Armenian dialect of Khodorjur
Resolutions of extrasyllabicity in Slovak
Metaphony in Italian and Spanish dialects revisited
Speakers' choices in language change
Some Irregular Reflexes of Proto-Malayo-Polynesian Vowels in the Rejang Language of Sumatra
Dynamic Dialectology: A Study of Language in Time and Space by Mieko Ogura