Q: What is tongue blocking?

A: Tongue Blocking (TB) is the technique where you take three or four holes of your harmonica in your mouth, and block some of them with your tongue. This way you can play single notes, (leave a hole either to the left or the right of your tongue) octaves (leave a hole to both sides of your tongue, exactly two holes apart) or chords (lift your tongue entirely -- BB

(FMI: "Tongue blocking" 17-20 May 95) (FMI: "Pucker at your peril!" 24 May 95 DT)