When noon sakinah or tanween is followed by one of six throat letters (ء ه ع ح غ خ), pronounce the noon clearly and fully with no nasal concealment or merging.

When noon sakinah or tanween is followed by one of six letters (ي ن م و ل ر), the noon merges fully into the following letter. Idgham has two types: with ghunnah for (ي ن م و), and without ghunnah for (ل ر).

When noon sakinah or tanween is followed by one of fifteen specific letters (ت ث ج د ذ ز س ش ص ض ط ظ ف ق ك), the noon is partially concealed with a nasal sound (ghunnah). This pronunciation is between the full clarity of izhar and the complete merging of idgham.

When noon sakinah or tanween is followed by ba (ب), the noon converts to meem (م) and is pronounced with a ghunnah. This conversion occurs because ba and meem share the same articulation point (the lips).