1) Noon Sakin and Tanween share the same pronunciation rules and sound. 2) They follow rules for Ithar (pronouncing throat letters with noon/tanween), Iqlab (flipping pronunciation to the throat), and Idgham (merging with next letter with or without ghunnah sound). 3) For letters other than ghunnah, the noon/tanween is hidden and only the ghunnah sound is made at the articulation point of the next letter.