Pausing on final letters
شمالوقف على أواخر الكلم
al-waqf ʿalā awākhir al-kalim
Stopping on a word normally silences its final vowel. But two further options exist: rawm, where the vowel is voiced so faintly it is barely audible, and ishmām, where the lips round to indicate a ḍammah without any sound at all. Abū ʿAmr and the Kufan readers are recorded as using all three.
How it sounds
Ishmām is visible rather than audible — a listener cannot hear it, only a watcher can see it.