Synchronization refers to the coordinated timing of the production of cues relative to the production of non-manual signals (i.e. information on the mouth).
Cued diphthongs have two parts – generally, the side or chin and the throat. For synchronization these locations should be timed to the mouth shapes that correspond. In the case of the diphthong /ɑɪīie/, the mouth should form /ɑäah/ while the hand is at the side and /ɪĭi/ when the hand contacts the throat. Instructors should monitor students to be sure that they do not articulate the entire diphthong on the mouth as the hand contacts the throat. This can happen because most vowels are produced with a single point of contact on the face. However, for appropriate synchronization, the hand and mouth should show each part of the diphthong at the same time.