High Quality Content by WIKIPEDIA articles! In historical linguistics, vowel breaking (sometimes called vowel fracture) is the change of a monophthong into a diphthong or triphthong. The change into a diphthong is also known as diphthongization.This is characteristic of the "Southern drawl" of Southern American English, where the short front vowels have developed a glide up to [j], and then in some areas back down to schwa: pat [pæj t], pet [p j t], pit [p j t].Some scholars[6] believe that Proto Indo-European language (PIE) i, u has a kind of breaking before an original laryngeal in Greek, Armenian and Tocharian, whereas the other Indo-European languages have monophthongs.