The harmonica is deceptively simple. Once you get serious about it, there are all sorts of words and phrases that can be confusing and misleading. So what is the difference between a blowbend and an overblow? What are they and how do you use them? Let's find out!
The missing notes
The diatonic harmonica has lots of notes missing, which means you can play simple melodies easily but sometimes you can't play a song using only the natural notes of the instrument. Here is a diagram showing just the natural notes of the instrument:
However, it's possible to add the missing notes by using special techniques to "fill in" the gaps that appear on the instrument. Different techniques will help you to fill in some of the extra notes; by using all these techniques, you can create a fully chromatic instrument which means you can (at least in theory) play anything.
One way of filling in extra notes is to use blowbends.
Blowbends, as the name suggests, are achieved by bending some of the blow notes. Only holes 7 to 10 will allow you to bend the blow notes. Here is a diagram showing the blowbends added in blue:
Holes 8 and 9 will drop by a halfstep (semitone). Hole 10 will drop by a full step (tone). Hole 7 will only give a microbend, so it has not been included on the diagram.
To produce the bend, you're actually activating the opposite reed in the slot, making it vibrate a half step above its natural pitch. For example, on hole 8 blow it feels like you're getting the G note to 'bend down to' Gb, but it is actually the draw reed vibrating a half step above its natural pitch of F. Even though two reeds are involved, the pitch will slide downwards smoothly.
Check out my blowbend harmonica lesson to learn more.
Another way of filling in missing notes is to play overblows. Overblows can be achieve on holes 1 to 6. Here is a diagram with the extra overblow notes in red:
When you play an overblow, you don't hear a slide in pitch from the natural note. When you create the right mouthshape and pressure for the overblow, the blow reed will actually choke, and the alternate reed will sound a halfstep higher than its natural pitch. Each hole from 1-6 will give you an overblow note. However holes 2 and 3 produce an overblow note which is more easily achievable elsewhere, so those notes have been excluded from the diagram.
Check out my Overblow Starter Guide to learn more.
What about overbends?
You may also have heard the word 'overbend'. Let me clarify what this means. In addition to overblows, it's also possible to play overdraws - extra high notes on holes 7-10 draw. Collectively, overblows and overdraws are known as overbends. Confusing, eh? Sorry, I didn't come up with these words; it's just the way it is!
Similarly with bending technique: you can play both blowbends and drawbends. Collectively these are known simply as bends. You will probably learn drawbends first, and then move on to blowbends, before learning overbends.
By adding all of the bends and overbends, you create a fully chromatic instrument as seen in this diagram:
To further confuse you, it's also possible to bend (i.e. alter the pitch of) overblows and overdraws. This may be necessary because overbends tend to come out a little flat of the desired note. It can also be a useful stylistic choice, and it is actually possible to alter the pitch of an overbend by a halfstep or even more.
Want to go into more depth? Check out this great guide on the mechanics of harmonica note bending from Steve Baker.
I hope this has helped to clarify the terms for you. Let me know in the comments!
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