Chords with More Than Three Notes
There are many ways to make chords with more than three notes. Usually, this is done by starting with a regular three-note chord, then adding another note (or two). For chords like this, the inversion you use matters a lot. For example, you might start with a C major chord, then add a D. If you put the D in the middle of the chord, you would play (from low to high) C, D, E, and G. When you play all these notes at the same time, it has a particular sound. I could try to describe it, but it would be better if you tried playing it. If you then try moving the D up an octave, it has a very different sound. It might sound more “open” and pleasing to the ear. If you try playing a D in a lower octave, so D becomes the lowest note in the chord, it sounds like a totally different chord. It sounds more like some kind of D chord, not a C chord.
In this experiment, you discover two things. One is that putting notes close together sounds different than putting notes farther apart. When the C, D, and E were right next to each other, it sounded different than when the C and E were in a low octave, and the D was in a high octave. The second thing is that the lowest note in the chord is very important, and it gives context for the rest of the chord. This is what happened when D was the lowest note. Keep these two things in mind when you experiment with adding notes to chords.
One common way to add a fourth note is to add the seventh note of the scale, creating a “one, three, five, seven” pattern. This creates what is called seventh chords. If you start with a C major chord and add a seven, you add a B. This is called a “C major seven” chord, and the chord symbol is Cma7 or Cmaj7. Try it to hear how it sounds.
You can also do this with minor chords. You can play a minor chord and add the seventh note of the minor scale. This is called a “minor seven” chord, and the chord symbol would be Cmi7 or Cm7.
In the section called “Chords in the Major Scale” I explained that you can move the “one, three, five” pattern up the scale to “two, four, six” and so on. This creates different chords that all come from one scale, so they sound normal when you switch between them. You can also do this with seventh chords. If you do this, you’ll find that the seventh chord that starts on the fifth note of the major scale is a major chord with a minor seventh. In the key of C major, the fifth note is G, and the seventh chord would be G, B, D, and F. In a normal G major seven chord, you would use an F# because F# is in the G major scale. When you lower the F# one semitone to an F, you have a major chord with a minor seventh. This is called a “G dominant seven” chord, and the chord symbol is “G7.” This chord is quite common in the key of C major. It’s actually more common than a Cmaj7 chord. The G7 chord creates a strong feeling that the C major chord should be played next. If the C chord is played after a G7, then there is a sense of coming home or ending a journey. Many songs in the key of C major end with a C chord preceded by a G7 chord. (This is true for all major keys).
Briefly, here is what happens when you move the “one, three, five, seven” pattern up the major scale, using roman numerals: Ima7, IImi7, IIImi7, IVma7, V7, VImi7, VIIdim7. These chords will sound fairly normal if you use them to create a chord progression.
Another way to add a fourth note is to change the bass note, the lowest note of the chord. In a normal C major chord, the lowest note is C. But what if you want the guitar player to play a C major chord, but you want the bass guitar player to play a D? The chord symbol for this would be C/D, and you would call it “C over D” if you were speaking. You could play this on piano by playing a C major chord in a high octave, and a D in a low octave.
Slash chords are often used in a way that doesn’t change the type of chord. C/E for example, still has the three notes of a regular C chord, but the lowest note would be an E instead of a C, the third instead of the root.
When the lowest note is not in the upper chord, a four-note chord is created. In some cases, it’s a seventh chord. C/A, for example is the same as Am7, so it’s probably better to write it as an Am7. C/F is kind of like a Fmaj7 mixed with a Fsus2. You could call it a Fmaj7sus2, but maybe that’s too hard for you to read.
Try experimenting with other notes. Play a C major chord (or any other chord) in a high octave, and some other note in a low octave. There are twelve notes that you could experiment with. Have fun!