I recently started practicing Messa Di Voce on certain notes.
I'm trying to do the exercise correctly, which means that if I start a note on an "AH" for instance in low volume, I need to get louder by only increasing the amount of air while keeping the entire configuration of the vocal tract stable.
I can do this exercise only to some degree of loudness. For instance if I started on volume level of 10% (out of 100), I can perhaps increase it only to about 30%, and I can't get louder than that without breaking the entire configuration and starting to strain in order to sound louder.
What should I do?
Work on Breathing?