I recently found out that when I form my broad vowels, my tongue goes flat. To my knowledge, a flat tongue is very bad! If I am correct, a flat tongue is a leading cause of a hoarse voice, lack of resonance, pitch instability, and much more. My question to you all is how can I stop my tongue from going flat? I try to slowly go from a narrow vowel to broad vowel. But when I do, the tongue just goes flat. I also tried to first form the broad vowel with my lips and not drop the jaw, vice verse. But still, I can not form the vowel without dropping the jaw. Any suggestions?