Everything you need to know about bending on the harmonica; the mechanics, methods and naunces, for your reference:
Draw bends can be a monster that many people find are difficult to deal with, however you may find you are closer to draw bending than you realize. As I tell my students if you are having a hard time getting a good clean 1, 2, or 3 draw note then you are on the cusp of getting a draw bend. Your tongue needs to be in the correct position to get a good bend.
That position involves raising the back of your tongue to the top of the back of your mouth and creating a jet stream. You will be creating a tunnel of pressure that will actually change the pitch of the note, lowering it in pitch. What some people find helpful when first learning to bend is to actually turn the harmonica up slightly and visualize the note changing. Another approach is to take a coffee stirrer or a small straw and try to suck in with more pressure. If you bend the end of the straw with your fingers you will find that your tongue will make its way into the correct position to bend a note on the harmonica.
Another approach is to go out and get a thick milkshake and try to suck it through the straw. If your tongue is in the correct position you should be able to make a “koh” sound. When you are saying “koh” your tongue is up in the back and down in the front which will allow you to create that pressure that you need. As you have seen you can change pitches 3 half steps/semitones on the 3rd hole but you may find it easier to learn to bend on the 1st or 4th hole draws.
Draw bends are available on holes 1, 2, 3, 4, and 6. There is a small bend available on the 5th hole draw but it is not a true half step. Another good thing to remember is that a bend does not require more air. The air is just accelerated. You are actually almost conserving air when bending: you are using a little less of it because of the pressure you are creating from your tongue.
Mechanics of Harmonica During a Bend
Many people don’t realize what is actually going on with the reeds when they are bending. The blow reed is also vibrating along with the draw reed during a draw bend. The reason that the 5th hole draw bend does not bend a full half step is because there is only one half step or semitone difference between the 5th hole blow and draw played without a bend (refer to the harmonica layout.)
You can see in the C harmonica there is an E on the blow and an F on the draw. These are only a half step apart (there is no E# or Fb. If you know about music theory they sometimes do use those notes but an E#=F and an Fb=E, for those of you who may have seen those notes used.). If you notice on the C harp the difference between the 1st hole blow and draw is 2 half steps (1 whole tone) which leaves room for the blow reed to bend a full semitone/half step (difference between C and C#). The 2nd hole difference between E and G is 1 ½ steps and leaves room to bend 2 half steps (or a whole tone/step.)
As you can see the 3rd hole has a difference of 2 whole steps or 4 half steps G to B. I show the following from B to G the draw bends descend that way from B to Ab and the G is the 3rd hole blow:
As you can see from the diagram the 4th hole is set up just like the 1st hole (C =1 blow, D=1 draw and 1 draw bent a half step is C# or Db). The Eb (above hole 4 blow) is actually an overblow, and is a more advanced technique, that will be mentioned in level 3. In the blow bends (mentioned in the following section) there is the same thing going on with both blow and draw reeds vibrating at the same time.
Blow bends are done with the same basic tongue position of the draw bends. You may find that a blow bend is more easily done by pushing your tongue slightly forward (the back of your tongue is still raised but moves a little forward in your mouth). You are saying “koo” but you are blowing instead of drawing. Blow bends are available in holes 8-10 and you will, like the draw bends, notice a lowering of pitch.
Hole 7 has somewhat of a blow bend but, like hole 5 on the draw bend, hole 7 is not a true half step bend because like hole five the difference between the blow and the draw is a half step. The Eb (hole 8 blow bend), F# (hole 9 blow bend), B and Bb (hole 10 blow bends) are working in much the same way as the draw bends only you are blowing instead of drawing and you will notice the difference between the notes still holds true (ie. The 8 hole blow is an E and the blow bend is Eb lowering the pitch, which is found between D (8 draw) and E in the chromatic scale. There are some players who only use a C harmonica to play in all 12 keys, like Otavio Castro, which is true chromatic playing and is truly a great feet on the diatonic harmonica, considering that a diatonic scale, what the harmonica was named for, is a 7 tone scale (ie. C D E F G A B).
As you can see by the layout of the harmonica the diatonic scale is found using only the notes on the harmonica with no bending or overblowing. The exceptions to that are of course found in holes 2 and 3 draw bends (F and A on the C harp) and 10 blow bend (B on the C harp). The diatonic scale is also known as a major scale as we mentioned before. The C# on hole 7 is an overdraw and like the overblows will be mentioned in level 3, for it is a more advanced technique.
An in intermediate bend is a bend found between the full range of the bend like on holes 2 and 3 draw. The 3rd hole draw intermediate bends are Bb and A where the full bend is Ab. Intermediate bends are useful because of their use in the blues scale, like the G blues scale which uses a Bb(3rd hole intermediate bend on a C harp). Intermediate bends are often hard to maintain pitch. You can use a tuner or a piano to check to make sure you are playing an intermediate bend in pitch. If you want to hear someone who uses intermediate bends in pitch, listen to some of Howard Levy’s recordings. Even Howard often only uses them as passing notes instead of resolving notes (notes you end on).
The dip bend is done by approaching the note either bent at first, releasing into another unbent note in a quick but smooth manner or playing the unbent note and gradually sliding into a bent note. It is frequently used to add a little flavor to a note.
Split Interval Bends
You can bend 2 notes of a split interval, such as in an octave, at the same time. It is also possible to bend one note of an interval to create an octave. An example would be if you bent the 2 draw a whole step and played the 5 draw without a bend you could form an octave. On the C harp that would be an F octave interval.
Draw Bend Vibrato
When trying to get a good smooth vibrato on draw bends you must use a lot of control with use of both the throat and the diaphragm. It requires a delicate breath and can sound very “unsmooth” if you don’t use a delicate touch. Throat vibrato is mainly a volume oscillation but can also be done using a slight pitch oscillation between bends. Remember that pitch oscillation is a slight wavering from note to note, as volume oscillation wavers between louder and softer.
Blow Bend Vibrato
Blow bend vibrato requires a little more control than draw bend vibrato because of the length of the reeds where blow bends are possible (holes 8-10). Some players find that the blow bend vibrato is easier because there is less play in the reed. Not as many bends as in the 2nd and 3rd hole draws.
Overbends (Overblows and Overdraws)
Overblows and overdraws require more narrow or tighter reed gaps and involve a lot more finesse than regular bends. Overblows and overdraws cause the opposite than normal reed to open rather than close, as happens in normal bending. In overblows there is an activation of the draw reeds and raise the note to ½ step above the normal draw note (unbent). Overdraws cause the blow reed to raise ½ step above the natural unbent blow note. As mentioned before a couple of overbend players are Howard Levy, Jason Ricci. Otavio Castro and Tinus Koorn(Overblow.com) both use only a C diatonic to play in all 12 keys, which requires a massive amount of overbends.