> in Mandarin "j", the part of the tongue that makes contact with the roof of the mouth is the middle
Never realized this. And after a few minutes of tounge-hyperconscious trying, I think some of us need some serious retraining to physically pull that off.
The fact that assuming this position necessarily thrusts the tongue very far forward in the mouth explains why the Mandarin palatal consonant series (q/j/x) can only be followed by the front vowels, /i/ or /y/.
If you're interested in learning to produce a foreign sound, I strongly recommend getting recordings (or live examples) to listen to and imitate. Working off a description will never quite get you all the way there.
Never realized this. And after a few minutes of tounge-hyperconscious trying, I think some of us need some serious retraining to physically pull that off.