Hearing Your Own Voice
Why does my voice sound different on a recording than in my own head?
When you speak or sing, you are hearing most of your voice via the vibrations travelling through your head, not sound travelling to your ears from outside. The sound waves that make up the sounds of your voice are travelling through a lot of bone, muscle and other tissues before they make it to the ear drum. Hence, it changes a bit, that's why every voice has a unique version that only its owner can hear.
How does this effect learning how to sing?
Sometimes you will make a sound that in your own head sounds full and rich and resonant, but if you hear a recording of yourself, you realize that you sound different. With your practice at home, the only way that you can be sure that you’re reproducing a helpful sound that you had done in a lesson is to try to reproduce that sound while recording yourself, then play it back, then compare it to the sound in your lesson recording. If you just go by what you hear, you run the risk of your ears misleading you. David Jones calls this phenomenon of our inner hearing "acoustical deception". So it’s best to go by sensations and their associated sounds on recordings of yourself.
Is that why you require I record my lessons and listen to them and take notes?
Absolutely, it will save you from tons of frustration and confusion and help you progress faster, and who doesn’t want that?