How much embouchure hole do you cover when you play?
If you cover too much embouchure hole, you’re going to compromise your sound, and of course, you’ll be flat.
If you cover too little of your embouchure hole, you will be sharp. And of course, your tone is also compromised.
The general rule is that about 2/3rds of that embouchure hole needs to be covered.
For me, I can get there by keeping my chin level, so I’m looking straight out and my chin is just level.
And I also think about keeping my fingers parallel with the ceiling.
If you do these three, most likely your embouchure will be covering the right amount.
But it’s not always true because we all have different thicknesses of our bottom lip.
But generally, 2/3rds of your embouchure hole should be covered.
Test your sound when you roll in and cover too much, when you roll out and cover too little. There’s a spot that’s just right.
Experiment with that, and use a mirror. It’s very helpful to use a mirror when practicing.
Let me know how this goes for you.
Watch me demonstrate this: FluteTips 7 Intonation Hole Coverage