This is a chart of a standard ten hole diatonic harmonica in the key of G that I copied from Wikipedia:

              1 2 3  4 5 6 7  8 9 10
       blow: |G|B|D |G|B|D|G |B|D|G |
       draw: |A|D|F#|A|C|E|F#|A|C|E |

As you can see, blowing in the first seven holes will produce a lower note than when drawing through that some hole. The last three holes produce the opposite effect. I personally find this confusing, and although I'm sure all you good harp players are used to this by now, I'm wondering why anyone would have set it up like this to begin with.


3 Answers 3


Actually it's the last 4 holes that produce the opposite effect you describe. I will explain why the original harmonica engineer set it up this way. First thing to note, is the harmonica was not originally intended to be an instrument used to play single notes. Had that been the case, the holes would be farther apart. Instead they are so close as to make it easy to play two or three or four notes simultaneously but very difficult to play single notes. Since you can either blow or draw, it only makes sense to make the adjoining blow notes and draw notes harmonize with one another, thus limiting which notes can go on the draw side and which notes can go on the blow side. A diatonic harmonica is designed to play all the notes in a single key. There are seven notes in each key so the G harp needs the notes G A B C D E and F#. It takes 3 notes to make a full chord so it only makes sense to have at least 3 notes on either the blow side or draw side. So the original mouth harp engineer set up the G harp such that no matter where you blow on it, if you blow any 3 notes you will be blowing a G a B and a D - the 3 notes of a G chord. So no matter which 3 holes you blow into on a G harp, you are blowing a G chord (possibly an inversion but a G chord nonetheless). Pretty cool. Engineered so that you can't possibly blow anything but a G chord no matter how hard you try. So if there are 3 of the notes in the scale on the blow side, the other 4 must be on the draw side. If there are ten holes, it is impossible to line up a repeating string of 4 notes on one side with a repeating string of 3 notes on the other so they simply don't line up. To make them line up would mean leaving out a note in the scale. On the draw side on a G Harp we have A D F# A C E F# A C E - a logical progression but unfortunately as noted above, they can't line up evenly with the repeating G B D pattern on the blow side.

Using A D & F# on the draw side of the first four holes allow you to play the V chord (D maj)in the key of G. Drawing hole 3 4 and 5 (F# A C) gives you the 7 diminished chord in the key of G (F# dim) and drawing holes 4 5 and 6 or 8 9 and 10 give you the 2nd Minor (Am) of G. The center position puts all 7 notes in the G scale together starting with the blow on hole 4 (G) then draw hole 4 (A) Blow hole 5 (B) Draw hole 5 (C) and so on through the F#. There is not a way to play a true C chord (the IV chord in G) but you can approximate the C chord by drawing C and E in hole 9 and 10 and then immediately blowing the G on hole ten (one of the two holes that you can reliably hit a single note on). Given the logistics of how far apart the notes can be on the same hole and the need to create a harmonious series of adjoining blow and draw notes and given that there are an odd number of notes (7) and even number of holes (10 - so the we can start and end on the root note) and in an attempt to include the ability to play as many chords in the key as possible, there is no better more logical way to arrange the notes. It would be set up differently if the harmonica was designed primarily for single note playing as is a trumpet and there was no provision for playing two or three notes at a time like a chord. Hope that makes some sense.

  • 1
    +1 for the theory behind it all. However, there are plenty of players who manage to get single note tunes - Larry Adler, Toots, Stevie Wonder come to mind. It's what your tongue's for! All harmonicas and blues harps have approx. the same hole spacings and blow/suck arrangement, including the chromatics. The 'suck' chord ends up as a dominant ninth without the root when all the holes are employed.
    – Tim
    Commented Jan 16, 2015 at 9:14
  • 2
    You are absolutely right about the fact that folks who practice and have acrobatic tongues have been able to master single note riffs and tunes. (I gave your comment a +1.) But I'm not sure whoever made the first harmonica envisioned this. So original intent and creative adaptation may be different things here. Just like whoever invented the 6 string guitar probably never intended for it to be played with a glass or brass slide. Yet creative folks found new ways to use the instrument. Commented Jan 16, 2015 at 17:09
  • @Rockin my problem with this theory is that it ignores the repeated note found at the second hole draw and third hole blow. One we can repeat a note, we can put the notes in any combination to match seven tones to eight holes. Also, imagine this blow :G|B|D |G|B|D|G |B|D|G| draw: |F#|A|C|E|A|C|F#|A|C|E|. Now its all nice and symmetrical.
    – user6591
    Commented Jan 16, 2015 at 17:39
  • 2
    @user6591 Nice and symmetrical yes - but no way to play a D chord which is the most important chord in the key of G other than the G chord. So the D in the draw row is essential for playing in the key of G. Commented Jan 17, 2015 at 7:05

A harmonica is set up, well, "harmonically". That would be rather tricky to reconcile when changing blow/draw orientation (man, it's worth having a bellows instrument just in order to be able to talk about push/pull instead) across octave changes. Now an octave has seven notes. If you are not going to change blow/draw when switching octaves, you have three notes on the blow as compared to four notes on the draw, at least in the part of the harmonica where you still have the full scale available.

And for accommodating a reasonable amount of songs, having two melodically useful octaves does not seem excessive. The lowest notes are only for accompaniment: there the selection is a bit different, fitting harmony better than melody.

In other words: how else would you have done that?

  • Pretty sure it's the same arrangement for accordions, too.
    – Tim
    Commented Jan 16, 2015 at 9:18
  • 1
    It's the same arrangement for melodeons. Accordions have the same notes on the blow and draw.
    – slim
    Commented Jan 16, 2015 at 13:44

The build of an instrument is dictated by the scales and tunings common in its culture or genre. These provide the 'target' towards which builders innovate.

In the case of the harmonica, innovation has been recent and conscious: an attempt to ease playability in various genres, facilitated by manufacturing advances.

In this sense, rather than trying to understand the instrument, listen to music from the genre it was built for, and what emotion or 'groove' players are trying to express.

The blues harp, for example, is a simple instrument built around the blues scale. If you understand this scale and are familiar with the blues 'groove', the layout of the instrument is more or less self-explanatory. Trust your ear, and all else will follow.

Orchestral or jazz harmonicas, on the other hand, are built around the notion of free play in any scale ('chromatic' harmonicas), leading to additional complexity - and challenges. High amongst these are the issues of coordination and breathing control, and, if with other classical players, reading music.

One of the more recent harmonica innovations are the 'Irish' harmonicas of Brendan Power. In themselves a simple advance, but vastly easing fast, rhythmic play in 'modal' Irish tunings.

That said, there are many types of harmonica. If nagged by the buying itch, rather than first looking for a harmonica, perhaps choose a musical genre that appeals, then look for the matching instrument..

Who knows. Maybe you'll discover an unexplored niche (Balkan? Chinese? Arabic?) in the world of harmonica design. ;-)

Trust. Your. Ear.

Postscript: for folk or traditional players, reading music is in many senses unnecessary ballast (and very few folk virtuosos can read a score). Try instead to play along with a slowed tune (using VLC or one of the many other audio/video tools), using an instrument of your own in the correct tuning (if necessary, ask another player for help getting this set up). You may be pleasantly surprised how quickly things fall into place.

A couple of weeks learning by ear and you will be playing your first tunes independently, and will have begun to develop the 'tunings intuition' that helps you hook up with others in a jam.

Try, on the other hand, to learn to read music and you'll be busy for the next year or two, but will have picked up little of the tension, speed and dynamics of the original recording. You may also have missed an opening in a local band..

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