The most complex English sounds of the vowel type are the triphthongs/'trIfTPNz/. They consist of a glide from one vowel to another and then to a third, all produced rapidly and without interruption.
The triphthongs can be looked on as being composed of the five closing diphthongs with /q/ added on the end.
| eI + q = eIq | qV + q = qVq |
| aI + q = aIq | aV + q = aVq |
| OI + q = OIq |
In fast speech the extent of the vowel movement is very small, except in very careful pronunciation. Because of this, the middle of the triphthong can hardly be heard and the resulting sound is difficult to distinguish from some of the diphthongs and long vowels.