Does the middle of the tongue touch the roof completely with the jeem, sheen, and ya ghair maddiyah, or should there be some space remaining for air to pass?

Question
Assalaam alaikum,
I wanted to ask the about the letters jeem, sheen, and ya ghair maddiyah . We raise the middle of the tongue to the roof of the mouth... does the middle of tongue touch the roof completely, or  should there be some space remaining for the air to pass?

Answer
Wa Alaikum Assalam Wa Rahmatullahi Wa Barakatuh,
The three letters (, , and the ) are all articulated from the middle of the tongue and what lies opposite it from the roof of the mouth, however the position of the tongue varies slightly for the three depending on their inherent characteristics.
 For the letter the tongue is closed tightly to the roof of the mouth so that there is no running of breath or sound.
For the letter , the tongue does not close off the articulation point at the roof of the mouth. There is a slight space in order for the sound and breath to run.
 As far as the , the tongue does not fully touch the roof of the mouth. There is a slight space in order for the sound to run, but without running of breath.
For more clarification you can see the lesson (in Arabic) by Sheikh Ayman at http://www.youtube.com/watch?v=k8LQtGUyOuU&feature=related . There are diagrams in the lesson that show the amount of closure of the articulation point for each of these three letters. 

Wassalam Alaikum Wa Rhamatullah