Holding phase

During the hold phase time, the vocal tract is completely closed. Air cannot escape through the nose because the velum is raised; air is trapped behind the closure. However, the lungs are still forcing air out of the vocal tract, so the pressure behind the closure builds up. You can feel the build-up of pressure behind a closure if you make a closure at the lips (as for [p] or [b]), and then make a conscious effort to breathe out. This is an exaggerated version of what happens in speech, but the mechanism is essentially the same.

The duration of the hold phase depends on many factors. In citation form and when before a pause, the hold phase is longer for [p t k] than for [b d g]. In other conditions (such as connected speech, like conversation), the average hold duration for all kinds of plosive is somewhere around 50 ms.