This lesson is about "faucets." I am using this metaphor in order to describe and explain the many ways that molecules of air become compressed in the vocal tract.
This is how singers actually feel the sensations to which many voice pedagogues mistakenly refer as "placement."
Perhaps thinking about a garden hose with an attatched nozzle will help you realize that you can guide an airflow to be felt almost anywhere in your vocal tract.
Say "ssss"......
Now say "sh........"
Now say the name Bach - making the "ch" continue for a moment or two.
You can feel that you are directing the flow of compressed air against differing parts of your palate. The confusion begins when you add sound from your vocal cords: the sound overpowers your feeling of airflow, and now you begin to "feel the sound" in those places, if your tongue is in the same positions. These would now become
"Zzzzzz"
Je......... (as in the Fernch word je)
The "ch" in Bach does not have a voiced cognate, but this tongue position can be very useful in creating what we call the "singer's formant."