Chords
A chord is when you play three or more different notes together at the same time. These notes are chosen based on how they relate to each other in terms of pitch. In typical Western music, chords are formed by arranging notes that are a third apart from each other.
Triads
The simplest type of chord, made up of three notes, is called a triad. The first note of a triad is called the root. The third note is crucial because it decides whether the chord is major or minor. If there's a minor third between the root and third, it's a minor chord. If there's a major third, it's a major chord. The fifth note in a chord is called that because it's a fifth interval from the root.
Diminished and Augmented Chords
A diminished chord is like a minor chord with a lowered fifth. (It includes a root, minor third, and diminished fifth). An augmented chord is like a major chord with a raised fifth. (It includes a root, major third, and augmented (raised) fifth). Augmented and diminished triads are seen as dissonant, which means they create tension or an uneasy feeling.
Sevenths
Incorporating a seventh chord within a certain key or scale typically involves stacking another third above the fifth of the initial triad. This results in a 1-3-5-7 structure, playing every other note in the scale. There are three main types of seventh chords: major, minor, and dominant.
Dominant seventh
Often referred to as the "seventh" chord, is formed by adding a minor seventh to a major triad. In essence, it's a major chord with a flattened seventh note, comprising a root, major third, perfect fifth, and minor seventh. This chord is sometimes notated as 1-3-5-♭7.
Major seventh
Major seventh chord is formed by adding a major seventh note to a regular major chord. This creates a chord with a root, major third, perfect fifth, and major seventh. For instance, a C Major 7 chord includes the notes C, E, G, and B.
Minor seventh
Minor seventh chord is made by adding a minor seventh note to a regular minor chord. This creates a chord with a root, minor third, perfect fifth, and minor seventh.
Other chord types
Sixths
A sixth chord is made up of four notes played together. It includes the root note, a major or minor third, a perfect fifth, and a major or minor sixth. The name "sixth chord" comes from that added sixth note.
Ninths
A ninth chord is a type of chord that consists of a root note, a major or minor third, a perfect fifth, and a major or minor seventh, along with the ninth note of the scale above the root note.
Elevenths
An eleventh chord is a type of chord that consists of a root note, a major or minor third, a perfect fifth, a major or minor seventh, and the eleventh note of the scale above the root note.
Altered, Suspended, and Power Chords
Altered Chords
Altered chords involve changing one or more notes from a basic major or minor chord. This alteration can include sharpening or flattening certain notes, creating a unique and sometimes dissonant sound. Altered chords are often used to add tension or colour to a chord progression.
Suspended Chords
Suspended chords, often denoted as sus chords, replace the third of a major or minor chord with either the second (sus2) or the fourth (sus4). These chords create a sense of suspense or anticipation, as they lack the definitive quality of major or minor chords.
Power Chords
Power chords are simple chords consisting of a root note and the fifth above it. They are commonly used in rock, punk, and metal music due to their straightforward and powerful sound. Power chords lack the third note found in major or minor chords, giving them a neutral quality that works well in aggressive musical styles.
Chord Inversion
Chord inversion happens when you play the notes of a chord in a different order. Normally, a chord starts with its root note at the bottom. But when you put a different note at the bottom it's called an inversion.
When you change the order of the notes in a chord so that the third note is at the bottom (3-5-1), you make what's known as the first inversion. The second inversion occurs when you put the fifth note of the chord at the bottom, followed by the root and third (5-1-3).
When you're dealing with extended chords, there are more than just two ways to arrange the notes, known as inversions. For instance, in the third inversion of a seventh chord, the seventh note is placed at the bottom; while in the fourth inversion of a ninth chord, the ninth note takes that position.
Chord Progressions
The key signature of a piece of Western music rules everything within that piece. Even though you might have loads of notes available on your instrument, only the ones allowed by the key signature can be used in that music.
So, let's say you have a song in C major. In that song, you'll only find the eight notes C, D, E, F, G, A, and B (sometimes with an odd sharp or flat thrown in as a rare exception allowed by accidentals). All the chords in the song will also be made up of some combination of these seven notes for each key.
- Diatonic chords: are created using the seven notes of a major key signature.
- Chromatic chords: are chords formed from notes outside the key signature.
- Minor scale mode: Understanding chords formed on minor keys becomes simpler when you understand there's essentially only one minor scale for each key signature. However, what makes minor keys interesting is the adaptable sixth and seventh degrees of the scale. These degrees can exist in two modes. It's common for compositions to incorporate both modes of these degrees within the same piece of music. Consequently, the minor scale can encompass up to nine potential notes.
Chord Leading
In music, any chord can transition to another chord within a key, but there are common sequences of chords that are used more often.
In major chord progressions, the main aim is usually to return to the starting chord, known as the tonic chord or I. All the other chords in the sequence act as a roadmap leading back to the I chord. This journey can be straightforward with just a couple of chords or complex with many different ones, but the ultimate goal is to land back on I.
In minor keys, the target is the vi chord of the relative major scale, which serves as the home chord.
While you can compose a song using any chords that sound pleasing to you (even ones from different keys) most chord progressions follow a few basic rules. These rules stem from the concept of chord leading, which suggests that certain chords naturally flow into others.
For instance, the V chord naturally leads back to the I chord. Although you can insert another chord after V, the most satisfying resolution is to proceed directly to I. Similarly, other chords have their related chords that they naturally lead to, and some chords can even lead to multiple other chords.
Reference
- The Complete Idiot's Guide To Music Theory by Michael Miller
- Music Theory For Dummies by Michael Pilhofer and Holly Day
- Harmony and Theory: A Comprehensive Source for All Musicians (Essential Concepts) by Keith Wyatt and Carl Schroeder