After speaking with many guitar players/students and seeing conversations on guitar forums, I have noticed that when the use of harmony is discussed the understanding is very limited. This is due to the fact that most people use their ear to find a harmony which is cool and all, but when you understand the theory it will open a bunch of new doors to possibility.
A harmony is simply when 2 or more notes are sounding simultaneously. In many different styles of music you'll hear two guitars playing the same melody or riff, but each of the guitars are playing different notes. That is the sound of a harmony. In the first part of this series of articles on harmony you will learn about a harmony type called parallel motion. In the articles soon to come (Understanding Harmony parts 2, 3, & 4) you will learn about similar motion, contrary motion, and oblique motion. Make sure to sign up for my newsletter so I can tell you when those are available. Okay, on to parallel harmony...
Parallel harmony is the most common type of harmony used. I guarantee that you have heard it before. It is likely that you have already used it even if you didn't know it. A parallel harmony is when the interval between the two notes being played is always the same interval type. An interval is the distance between two pitches. You can use 3rd's, 4th's, 5th's, 6th's, 7th's, and 9th's. Those numbers are all intervals that are diatonic to a specific key. Diatonic means notes that are in the key or scale.
For those who don't understand what those numbers mean or represent, I will give you a brief explanation by using the key of C major. The notes in the key of C major are C-D-E-F-G-A-B. Let's try harmonizing by intervals of a 3rd starting with the C note. If we are harmonizing the C note by using a 3rd that simply means you are using the note that is three notes higher than the C note in the C major scale (you must count C as one). So let's find that third note; C(1)... D(2)... E(3). Our third note above C is E. So, if you play the C note and the E note at the same time you will be harmonizing by a 3rd. Let's find a 3rd above the second scale degree of C major scale. The second scale degree in the C major scale is the note D, so D(1)... E(2)... F(3). Our third note above D is F.
Following is a diagram of thirds in the key of C major (the arrows are connecting the notes that are a 3rd apart):
I also want to remind you that the repeated C and D are both octaves of the 1st C and D. Going into octaves will be necessary for the harmonizing process.
For the remaining intervals the process will be the same. Below are examples of each interval in the key of C major. The 2nd note in the parenthesis is higher than the first note in the parenthesis. If the note is lower case that will mean it is more than an octave or higher than the uppercase note.
Use the fret board diagram below to locate these notes on your guitar:
I want to quickly point out why I didn't include the interval of a 2nd on the previous list. Intervals of a 2nd, such as B & C and F & G, are harsh to the ear. This is why we use 9th's instead. 9th's are simply 2nd's an octave higher. The distance of the octave smoothes out the otherwise harsh sound. You can move any note into the octave for a different sound. This is how we come about 9th, 11th, and 13th chords.
Now you can utilize harmonies on your own, or with another guitar player and/or any other instrument. It is commonly done both ways. If you are playing both notes on your own then it is referred to as a double stop. Double stops are common in many styles if not all; from classical to country, metal to folk, and punk to jazz. Now that's diverse! To use double stops you will place each note on a separate string, and then play both strings together. For example you can put a finger on the A note (2nd string, 10th fret), and a finger on the C# note (1st string, 9th fret) and play those together. That will result in a harmony of a 3rd.
Another way to harmonize with another guitarist's melody is by utilizing the modes of whatever key the melody is in. For example if you want to harmonize a melody in the key of C major by using thirds then you can simply use the third mode of C major which would be E phrygian. Try having one guitarist ascend or descend through the key of C major note for note while you do the same in E phrygian. This will achieve a diatonic harmonization of thirds. Following is a diagram of how the notes in these two scales pair up:
C Major: C-D-E-F-G-A-B
E Phrygian: E-F-G-A-B-C-D
If you want to harmonize in 5th's you can use the Major scale's relative Mixolydian mode (Mixolydian is the 5th mode of the Major scale). You can use this method with all the Major scale modes.
All of the previous information was in relation to a specific type of harmonic motion known as parallel motion. Parallel motion is when the harmonies are moving in the same direction and by the same interval. There are three other types of harmonic motion, and that's where it really starts getting interesting. In my next article on harmony we will discuss next of the three remaining types of harmonic motion, similar motion. Enjoyed this article? Sign up for my newsletter to immediately receive a free video filled with examples of everything discussed in this article played on guitar plus more! Until then I'll leave you with a TAB example of a 2-part guitar harmony using 3rd's: