Two parts of the overblow
A normal diatonic harmonica has two reeds for each slot, one blow reed and one draw reed.
When playing a (draw) bent note these reeds work together, the draw reed vibrating at a pitch lower than the one it is tuned to and the blow reed vibrating at a pitch higher than the one it is tuned to.
When playing an overblow only the draw reed sounds while the blow reed is choked.

Playing the overblow can be seen as to consist of two separate parts:

1. Getting the blow reed to stop sounding.
2. Getting the draw reed to sound.

Though the objective in overblowing is to get the draw reed to sound while blowing into the slot, choking the blow reed is the important first step to achieving this.
User Contributed Notes
18-04-2008 14:28
The translation of the previous comment written in Portuguese is roughly this: "I would like to have all the techniques concerning the overblow since I live in Brasil and have no acess to that material, thank you,Gideão"
I know years have past but I figured some people would like to know.
03-09-2005 11:55
I hope that that is a good thing?
02-09-2005 14:44
Gideão josé de moura
queria ter todos as tecnicas do overblow,pois moro no Brasil e não tenho acesso a esse material, muito obrigado,gideão