I am trying to correctly pronounce ш (/ʂ/), ж (/ʐ/) and щ (/ɕɕ/), so I must learn the 3 related phonems: /ʂ/, /ʐ/ and /ɕ/. I am familiar with the phonems /ʃ/ and /ʒ/ from English and, as all these phonems are fricative, the difference can only be in labialization and tongue position.
I have read on https://en.m.wikipedia.org/wiki/Labialization that the Russian fricative phonems does not have the slight rounding usually done in English fricative phonems.
Regarding the tongue position, it is my understanding that, if I start with the tip of it in the front upper region of the mouth, touching the back of the upper teeth, and bring it all the way to the center of the roof of the mouth (palate) (the same place where my tongue is when producing /j/), I will pass through the phonems /ʃ/, /ʂ/ and /ɕ/. /ʐ/ will become easy after I have figured out where /ʂ/ is done, as the only difference is vocalization. Am I right about all this?
I got confused after seeing this video: https://youtu.be/zltpo15toe0 . At 8:00, it is said that, to get to /ʂ/ from /ʃ/, you must drop the pitch by flattening out the rounded position of the tongue done in the latter. However, I do not feel any "rounded position of the tongue" in /ʃ/, so I have no idea how to "flatten it out". Is that related to the labialization change I mentioned above? Even if it is, my tongue tip would still be in the same position of /ʃ/ and I thought that, in order to pronounce /ʂ/, the tongue tip should be not in the alveolar ridge, but a little backwards, between the alveolar ridge and the palate. This video also says that /ɕ/ is done by doing the opposite and raising the pitch by rounding the tongue even more towards the roof of your mouth and keeping your tongue tip near your lower teeth. That seems to imply that /ʃ/ is between between /ʂ/ and /ɕ/ , what goes against my theory above.