Question

I noticed a Qur'an reader reciting an aayah at the end of which his last letter was saakin.  Then he circled his two lips like a dhammah, but made no sound.  I found this fascinating-could you explain what he was doing?

Answer

It sounds like the reader was doing what is called , which is a circling of the two lips after putting a presented sukoon on the last letter of the word to show that the original dhammah that the last letter had.  There is no accompanying sound with the , so it can only be observed by watching and never detected by only listening. This is an acceptable way of stopping on a word that has an original dhammah on the last letter.  You must have been observing someone very accomplished in recitation, or someone teaching recitation at an advanced level as this technique is only taught at higher levels and generally used by shuyookh (plural of sheikh) and their students.