More Consistent Shakes - Part 1 (Mechanics of a Good Shake)
The Shake (also known as a Warble or Trill) is one of the all-time great sounds on the harmonica. The shake is used as a substitution for a single note. Using the 4 draw for example... play the 4 draw first, and then move to the 5, and then back to the 4, repeating the process (4 5 4 5 4 5 4 5 etc.). The speed of the shake is up to you, but generally floats in rhythm somewhere between that of a triplet and sixteenth-note triplet. You can move your head, hands or both for the shake... this is up to you... but you may find choosing one (head or hands) and sticking to it best. It's generally recommended that you use your head, though this is not a hard rule.
Here are some helpful tips on your shake...
1) Relax all your muscles (tongue, mouth, neck, back, arms, etc.). Tense muscles mess up the shake.
2) Start with the bottom note... this is the note you're adding color to, so it should be presented first.
3) If your bottom note is a draw (holes 1-6), start it with a dip (a bend that releases quickly). Don't start your shake until the bend of the dip is fully released.
4) If your shake starts to sound strange, you most likely drifted too far to the right (or possibly left). Too be exact... after your bottom note is played, your embouchure (the opening of your mouth where the air goes through to play the harmonica) is centered between the two holes.
5) As you perform the shake, your nose should be centered. In other words, when you're between the two holes, your nose is at 12 O'Clock. When playing the 4 your nose is at 11 O'Clock and the 5 you're at 1 O'clock.
Practice this in front of a mirror and I'll take you to the next step tomorrow.