Here is a quick explanation of Modal Interchange. It is a technique that is used commonly in all genres of compositon. It is very easy to identify and study in western pop and Jazz compositions. Next week I will be posting an analysis of the Beatles song “Julia” and it will focus on the use of Modal Interchange to color melodies and create alternative harmonies.
In western music theory the world revolves around the 7 tone Major Scale. As my first theory teacher in Houston, Kelly Dean, told me, “The major scale is the center of the universe.” Nearly every song that exists can be broken down to a collection of major scales and their relative Modes.
A mode is a permutation of a scales note order. For example if you take the first 7 tones of a scale and put them in order (C D, E, F, G, A, B) then start from a different place in the chain and reorder them, you will wind up with the same chain of materials but a different interval construction. For example, the 2nd mode would start from the 2nd place in the order (D, E, F, G, A, B, C) or the 3rd (E, F, G, A, B, C, D). This is the basic idea.
What makes one mode unique from another is it’s individual interval construction. The 1st mode of the Major scale is built of Whole-steps and Half-steps in this order: W, W, H, W, W, W, H. If we use these letters instead of the note names the second mode looks like this: W, H, W, W, W, H, W. Here is a table of the traditional 7 modes and their constructions as found in the key of C Major (Ionian). On the left is the Greek name for each mode, followed by the note names, Whole-Step/Half-Step construction, and then the scale numbers.
Notice in this chart I have reordered the notes of the 7-note major scale. A Modal Interchange chart instead shows each modal structure starting from the same root pitch. The C, D, E, F, G, A, B, C, pattern stays constant now and is affected by the changing interval structure. Accidentals show the intervallic differences.
Say you have the C major scale. Your basic chords are C, D-, G, and F. Now, if you wanted an F# in the melody, you could use this table to find the mode that has the F# and “borrow” a chord from that version of the C scale. In this case the mode is Lydian. Change your scale to C Lydian for a moment and The F# can be borrowed and used now in your progression. Alternatively you could use the Locrian mode and borrow the Gb (F#). If you did that, your D- chord would have totally changed shape, but you could have an Eb- or a C half-diminished chord (C-7b5) instead. Modal Interchange exposes extra options for coloring a change in the melody. Once you find your melody note in the grid, you can experiment with all of the different possibilities.
A few common uses of this technique are:
IV to iv- (from Aeolian). This is really popular in everything from Rock, Blues, and Jazz to Church and Gospel.
II7 (from Lydian). This also can be found very very often in many varieties of song.
bII (from Phrygian). This is common to many performers in Jazz since the late 50s or early 60s. It is used as a way to end songs or as a chord during a solo progression. Also, it can be associated with the classical Neapolitan chord, which is an early usage of the same Modal technique.
I didn’t learn about Modal Interchange until I started studying Jazz and American songbook compositions. Its use can of course range from very simple to quite complicated. One of the guys that uses it very clearly is Joe Henderson. Take a listen to his arrangement of “Without a Song In My Heart” or his composition “Serenity.” Both songs use a pretty wide spectrum of tricks from this area.
Next week I’ll be posting an analysis of one of my favorite Beatles songs, “Julia.” I learned the tune and did an arrangement for my brass group a few months ago and was amazed by the cleverness in the chord progression. The song has a kind of etherial quality that is generated by the shifting sounds.