Finding the best Mode to play a song in

Article Written By: Robert Coble (Bob) and posted to
Christian Harmonica on April 19 2006
Used By Permission

Question: How do know which mode to play a song in ?


Believe it or not (Ripley), this one is actually easier than it seems, IMHO.

The starting point is the key signature. That establishes the "natural" notes in the corresponding scale (NOT the mode). That means figuring out the key based on the number of sharps or flats (or absence of sharps/flats, in the case of "C" major or "A" minor).

That part is drop-dead EASY, if you made one of those Circle of Fifth wheels that I mentioned previously. The corresponding key signature (number of sharps/flats) is found directly under each key on the outer wheel.

Again, let's use your example of playing the song "Jesus, Lover of My Soul" (the worship chorus) in "G" major. Looking at "G" on the wheel, that's a key signature of 1 sharp. Hmmm, that's a start, but WHICH note is that 1 sharp?!?

Put the little red arrow at "G". Now read off the NOTES on the outer wheel that correspond to the UPPERCASE Roman numerals on the inner wheel. Flattened out, it should look something like this

I = G
II = A
IV = C
V = D
VI = E
VII = F#

The seventh scale degree is the sharped note F#. Note that we are laying out the notes of the "G" MAJOR scale, which is the same as IONIAN mode.

Once we know what notes are in the scale, we can determine the notes in each of the "modes".

It is a truism of Western music that almost all of it starts on or ends with the tonic chord. (Yes, Amelia, there ARE exceptions - to everything theoretical.) In plain English, that means the song "resolves" (will end on) a chord made up of (at least) scale degrees 1, 3 and 5 of the corresponding scale AND mode.

Here are the 7 modes using the "G" major scale as the basis:

Starting at scale degree 1: G--A--B-C--D--E--F#-G (IONIAN)
Starting at scale degree 2: A--B-C--D--E--F#-G--A (DORIAN)
Starting at scale degree 3: B-C--D--E--F#-G--A--B (PHRYGIAN)
Starting at scale degree 4: C--D--E--F#-G--A--B-C (LYDIAN)
Starting at scale degree 5: D--E--F#-G--A--B-C--D (MIXOLYDIAN)
Starting at scale degree 6: E--F#-G--A--B-C--D--E (AEOLIAN)
Starting at scale degree 7: F#-G--A--B-C--D--E--F# (LOCRIAN)

All of these modes have a key signature of 1 sharp:

"G"  IONIAN     (Same notes as the major scale)
"E"  AEOLIAN    (Same notes as the natural minor scale)

Determine the last chord in the song (usually ending on a whole note, dotted half note, or tied notes, so that the last tone is held).

I'll assume that you know how to read the notes of that last chord, one at a time, on the sheet music. (This does NOT require sight reading ability; you do this process away from the harmonica BEFORE you try to play the song.)

Let's ASSUME (for illustrative purposes ONLY) that the basic triad (scale degrees 1-3-5) of that last chord contains the notes E-G-B. That's NOT the basic triad for the tonic chord of "G" major, which would be G-B-D! (Ignore any inversions; I'll assume root "inversion".)

If you look back up at the notes of each mode above, you'll see that the mode which has scale degrees 1-3-5 corresponding to E-G-B is the AEOLIAN mode. That's just a fancy way of saying that the song is in Em (E minor)!

As another example, let's assume that the basic triad of that last chord contains the notes A-C-E (scale degrees 1-3-5). The song would then be in A DORIAN, which is a kind of minor key.

"And so it goes" (to quote Linda Ellerbee).

Why is this true? Because most Western music wants to start on the tonic, move away from the tonic, and eventually return to the tonic. You use that knowledge to figure out things about the song, such as the closest mode.

BTW, here's a little more information about the modes.


And now for more of that theory stuff embedded in that tool.

If you place the red arrow at the major key, the green box will be pointing to the corresponding relative minor key (the natural minor key with the same key signature as "G"). For example, if you place the red arrow at "G", the relative minor key will be "E". If you look at the info above, you find that "E" (with 1 sharp in the key signature) is AEOLIAN mode.

So what is the big deal about THAT? Just this: Since the natural minor scale (AEOLIAN mode) uses exactly the SAME notes as the relative major scale, you can play minor songs on your major key harps!!!

Where does that natural minor scale start on a 10-hole Richter-tuned diatonic? ALWAYS on the 6th scale degree note. Use the following chart to "finger" it out:

Hole 4 blow = Scale degree 1
Hole 4 draw = Scale degree 2
Hole 5 blow = Scale degree 3
Hole 5 draw = Scale degree 4
Hole 6 blow = Scale degree 5
Hole 6 draw = Scale degree 6 (Pay very close attention HERE!)
Hole 7 draw = Scale degree 7
Hole 7 blow = Scale degree 8

Starting on hole 6 draw, there is a COMPLETE natural minor scale available, going "up" the harp. This is the relative minor (AEOLIAN mode) corresponding to the key of the harp (assuming the harp is tuned for a major key).

The same is true for all of the other modes. Because the notes remain the same for all modes (based on a particular major scale), there will always be a starting location on the diatonic harp which allows all notes of each mode to be played (without bending or overbending).

Here are the starting locations for ALL modes (assuming you are playing "up" the harp from the low end towards the high end):

Hole 4 blow: IONIAN mode  (major scale) - STRAIGHT harp
Hole 4 draw: DORIAN mode - DRAW (or slant or double-crossed) harp
Hole 5 blow: PHRYGIAN mode
Hole 5 draw: LYDIAN mode
Hole 6 blow: MIXOLYDIAN mode - CROSS harp
Hole 6 draw: AEOLIAN mode (natural minor scale)
Hole 3 draw: LOCRIAN mode

Note that a complete set of scale notes for LOCRIAN mode beginning on hole 7 draw is not available without blow bending hole 10. That's the only reason for starting the LOCRIAN mode on hole 3 draw.

Note that a complete set of scale notes for LOCRIAN mode beginning on hole 7 draw is not available without blow bending hole 10. That's the only reason for starting the LOCRIAN mode on hole 3 draw.

For traditional church music, LOCRIAN is virtually unused. It was merely a "theoretical" mode for a long time - until jazz began to evolve from the basic blues structure. Now it is used quite a bit for improvization in jazz. Go figure...and NO, I'm N-O-T a "jazzer", although I love the early (pre-bebop) jazz sound!

Of course, with bending/overbending, you can play these scales (and lots more, such as pentatonic, blues, etc.) starting at other places on the lowly diatonic "toy" harp. Who woulda thunk it?!?

I think I've demonstrated WHY some knowledge of music theory is VERY useful to harp players. You may not sight read sheet music, but theory can help you to (eventually) have a better understanding of what can be played. It's like a toolbox full of different kinds of tools: it extends the precision that you can bring to bear on the problem at hand. Without some knowledge of music theory, you are only limited by your imagination - and some people never realize just how limited their imagination is!

Here are some philosophical tidbits:

The whole world looks like a nail - to a five-year old with a hammer!
A fool with a tool - is still a fool!

[Another little bit of tool trivia: the parallel blue lines mark the parallel minor. (I'll leave that unexplained until asked, because it's not germane to the current discussion.)]

Please remember that I "warned" you that one question (and answer) WILL lead to more questions - and answers, hopefully. LOL! That's how we LEARN, and I hope this is still clear. Enjoy the learning process!

Still "foolin'" with my harps!
Crazy ('bout harp!) Bob

Thanks Bob, For the fine article

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