Music theory can be a complex subject, and for many musicians, understanding the terminology is essential. One term that is often used in music theory is the “fourth.” Whether you are a beginner or an experienced musician, understanding what a fourth is and why it matters in music can help you become a better musician.
What is a Fourth?
A fourth is a musical interval that spans four notes on a scale. In other words, it is the distance between two notes that are four scale degrees apart. For example, the interval from C to F is a fourth because F is four steps (or scale degrees) above C. The interval from G to C is also a fourth, as C is the fourth note in the G major scale.
When playing a fourth, the notes are typically played together, giving them a rich, harmonious sound. This interval is often used in music to create tension and release, and it is a fundamental building block of many chords.
Types of Fourths
There are two types of fourths: perfect and augmented. A perfect fourth is the interval that spans four notes in a major scale, while an augmented fourth is one half-step larger. For example, the interval between C and F is a perfect fourth, while the interval between C and F# is an augmented fourth.
Augmented fourths are uncommon in traditional Western chord progressions because they have a dissonant sound that can be difficult to resolve. However, they are a common feature of blues and jazz music, which often use augmented fourths to create tension and add a bit of dissonance to the melody.
Why Does a Fourth Matter in Music?
The fourth interval plays an essential role in music, particularly in Western music. Many common chord progressions are based on the intervals of the fourth, including the Circle of Fifths and the blues progression.
The Circle of Fifths
The Circle of Fifths is a diagram that represents the relationship between the twelve tones of the Western chromatic scale. Each note on the circle is a perfect fifth above the previous one, moving clockwise around the circle. When you follow the circle clockwise, you are going up in fifths, while moving counterclockwise is down in fourths.
The Circle of Fifths is a useful tool for understanding the relationships between different musical keys, and it can be used to determine key signatures for a piece of music. Because each note is a fifth (or fourth) away from its neighbor on the circle, chords and melodies that use these intervals tend to sound natural and pleasing to the ear.
The Blues Progression
The blues progression is a chord pattern that is commonly used in blues music. It is based on the I-IV-V chord progression, which uses the intervals of the fourth and fifth to create a sense of tension and release. In C major, for example, the I-IV-V progression uses the chords C, F, and G. The C and G chords are a perfect fifth apart, while the F and C chords are a perfect fourth apart.
The blues progression is often used as a basis for improvisation, as it provides a simple, repetitive structure that allows musicians to focus on playing their instruments or singing. By using the intervals of the fourth and fifth, the blues progression creates a sense of familiarity and comfort for the listener, making it a popular choice in many styles of music.
How are Fourths Used in Music?
As mentioned earlier, the fourth interval is used in many different ways in music, and it is a fundamental building block of many chords and chord progressions. Here are a few of the most common ways that fourths are used in music:
Power chords are a type of chord that use only the root note and the fifth. Because they do not include the third interval, they are neither major nor minor, giving them a neutral sound that works well in many styles of music. Power chords are often used in rock music, where their simple structure and powerful sound make them a popular choice for heavy guitar riffs.
Power chords are often played with an open fourth, where the fifth is played on the string above the root note. Playing the fourth and fifth together gives the chord a rich, harmonious sound that is perfect for creating an epic, timeless feel.
Suspended chords are chords that use the fourth interval in place of the third. This gives the chord a suspended, unresolved sound that can create tension and anticipation. Suspended fourth chords are often used in rock and pop music, where they are a popular choice for creating a sense of drama and excitement.
As mentioned earlier, many common chord progressions are based on the intervals of the fourth. These chord progressions include the Circle of Fifths, the blues progression, and many others. By using the intervals of the fourth and fifth, these progressions create a sense of familiarity and comfort for the listener, while also providing a structure that musicians can use to create melodies and improvisations.
The fourth interval is an essential building block of music, particularly in Western music. Whether you are playing power chords, suspended chords, or a complex chord progression, understanding the role that the fourth plays in music can help you become a better musician. By mastering the intervals of the fourth and fifth, you can create rich, harmonious sounds that will impress and delight your audience.
- What is a perfect fourth?
- What is an augmented fourth?
- How are fourths used in music?
- What is the Circle of Fifths?
- What is the blues progression?
A perfect fourth is an interval that spans four notes in a major scale.
An augmented fourth is a fourth interval that is one half-step larger than a perfect fourth.
Fourths are used in many ways in music, including in power chords, suspended chords, and chord progressions.
The Circle of Fifths is a diagram that represents the relationships between the twelve tones of the Western chromatic scale.
The blues progression is a chord pattern that is commonly used in blues music. It is based on the I-IV-V chord progression and uses the intervals of the fourth and fifth to create a sense of tension and release.
1. Benward, B., & Saker, M. (2003). Music: In theory and practice (Vol. 1). McGraw-Hill.
2. Piston, W. (1987). Harmony (5th ed.). W.W. Norton.
3. Watson, A. (1994). The rhythm section. Hal Leonard Corporation.