To get an airtight seal while tongue blocking, here's what to do:
- Turn your head slightly to your left
- Then, play the harmonica from the side of your mouth while tongue blocking
While tongue blocking, we use our tongue to block out holes on the left side of our mouth, and play notes from the right side. So, playing the harmonica from the right side of the lips provides a better seal around the note that you're trying to play.