My experience teaching shofar has reached a similar point. In many causes, I can hear a person's technique without seeing what they are doing, even via a telephone call. In fact, I have been able to telephonically teach several individuals to blow shofar.
One recent student offers the following accolade.
I didn’t know that I could learn to blow shofar over the phone. It doesn’t matter that Michael’s in L.A. and I’m in Atlanta. He hears what I am doing and offers suggestions that improve my playing. Without his encouragement, I would never have tried to learn to play, but his humor and expertise keep me going. His generosity with his time is inspirational." Rabbi Elana Zelony, Congregation Shearith Israel, Atlanta.Send me an email at shofarot at gmail.com if you want to schedule a lesson.