Here's something to write down in your notebook: We learn to feel what happens in the vocal tract after we make the sound we have made rather than before.
Got that? If you keep this in mind, then you will be way ahead of the oh-so-smart grad student who's just discovered Manuel García's groundingbreaking treatise (the first to assign physiological causes to tone) and believes he can learn how to sing though an understanding of vocal mechanics and raw manipulation.
You'd be surprised how many people think this can be done. All you have to do is sit through voice juries at your nearest university and you will hear things like: "She doesn't keep her larynx down!" He doesn't lift his soft palate up enough!" "Where is the support?" "Oh, that was a fine legato! She really used her core muscles that time!"
We all too often equate knowledge about observable phenomena as being equal to its creation. However, old Italian school voice teachers, who approached the teaching of singing from an empirical perspective, would not agree. They were "vowel first" people, not move this muscle to get that sound folks.
We see this in Klein's text in Hidden in Plain Sight: The Hermann Klein Phono-Vocal Method based upon the Famous School of Manuel García in his teaching regarding "singing position." There, Klein instructs the student to "first sound the vowel "ah" in the speaking voice. This should be done with firm utterance, not very loudly, but upon what seems to be a rather deep, reverberant sound."
Got that? Klein is asking the student to "sound" a vowel in a very specific manner. There is a lifetime of instruction in this teaching. Why? Because to do what Klein asks requires the student to listen to what he/she is doing.
The result? Klein tells the reader: "This action will be found to press the larynx down to a slightly lower position in the throat than it ordinarily occupies. The deeper the speaking sound the lower that position will be. Observe the nature of the sound thus uttered, and see that it be easy to sustain, musical, and pure."
You make the sound and then observe the result. As such, listening comes first, which leads to an experience/understanding of cause and effect.