Michael Rubin tells us:
As you go from one standard richter tuned harp key to another, the hole placement of any position's scale degree tones remains the same. What changes are the actual notes, but the relationship between the notes as measured by half steps (one half step in distance is one note to the very next note in the western chromatic scale) remains the same. This means if you learn to play in a position on one harp, you can physically play the same way on another harp and get the same musical phrase transposed into another key. Learn one harp, learn them all.
This is, indeed, the way to learn multiple position playing,. For example, Draw 6 is the 6th degree of the scale in First Position, 2d degree in Second, 5th degree in Third, root in Fourth, 4th degree in Fifth, 3rd degree in Twelfth. You just learn which holes correspond to what degree of the scale in which position. The particular key of the harmonica makes no difference whatsoever.
The problem which eventually arises is that other musicians usually tend to speak in terms of note names (for example, A, Bb, C, etc.) NOT degrees of the scale. So, at some point one needs to learn to “spell” the scales unless the musicians you work with are willing to put up with you constantly asking them, “What degree of the scale is that?” But this is sort of a happy problem to confront since it means that the musicians talking to you consider you to be a musician, and view your harmonica as a legitimate musical instrument. A competent musician should know his or her instrument well enough to know which notes are found where. However, I must confess that, in most keys, I still am more facile thinking in terms of degrees of the scale. Since I’m self taught and play no other instrument, I never started out by having to learn to spell scales. But it’s a work in progress.
Although I have no formal musical training, I have had the good fortune to play with some really good musicians over the years and from them I picked up a practical basic working knowledge of music theory, at least as it relates to harmonica. Now, I’m at the point that the guys I play with expect me to communicate in terms of note names. But you actually don’t need to be able to do that in order to know HOW to play in multiple positions. However, to understand WHAT the other musicians want you to play, and to select a position that allows you to actually play it, knowing the note names sure can be helpful.
FWIW,
JP