What is the Difference Between an Extended Chord and a Secondary Dominant Chord?

Understanding the nuances of chords is fundamental to both amateur and professional musicians, particularly in harmonic analysis and composition. One common confusion arises between two distinct types of chords: extended chords and secondary dominant chords. Each has its unique role and application within the framework of music theory, creating a rich and varied palette for composers and performers alike.

The Concept of Extended Chords

An extended chord is a type of chord that includes notes beyond the basic triadic structure. A triad consists of three notes, typically the 1st, 3rd, and 5th of a scale, forming a root, third, and fifth. Extended chords add additional intervals above the seventh, such as 9ths, 11ths, and 13ths. This expansion can create more complex and colorful harmonic textures, often used to add depth and richness to a musical piece.

Extended chords are simply triads with additional thirds added beyond the 7th. In essence, a 9th, 11th, or 13th chord falls under this category. For example, a C major 9th chord would be C-E-G-B-D, adding the 9th (D) to the C major triad (C-E-G).

The Role of Secondary Dominant Chords

A secondary dominant chord, on the other hand, is a dominant chord (V) that functions as the dominant to a chord other than the tonic (I). In simpler terms, it is a chord that operates as a temporary dominant to guide the listener's ear towards a different chord. This function is crucial in creating harmonic tension and release, making the harmonic journey more interesting and expressive.

Secondary dominant chords are commonly used to intensify the movement towards the dominant chord (V7) or any other chord that does not belong to the home key of the piece. For example, in the key of C minor, instead of using the usual F minor chord, one might use a G7 chord (the dominant of F minor) to enhance the sense of resolution and movement towards the F minor chord.

Here is a common example to illustrate this concept: in the key of C minor, a typical progression would be C minor, F minor, and G7 before resolving to the C minor chord. By using a secondary dominant, the progression can be modified:

C minor - D7 - G7 - C minor

In this example, D7 is the secondary dominant, as D is the dominant tone to G, which is then treated as the tonic for a moment. This technique is not only found in classical compositions but also in jazz and other modern genres.

A Practical Example

To provide a more concrete example, consider Chopin's Waltz in C minor, Op. 64 No. 2. The opening four chords are as follows:

C minor - F minor - G7 - C minor

By substituting the F minor chord with a D7 (the dominant of G7), the progression takes on a more dynamic and intriguing quality:

C minor - D7 - G7 - C minor

This modified progression, C minor - A7 - D7 - G7 - C minor, is not only a fascinating harmonic journey but also a common technique in Latin jazz. The A7 and D7 chords further emphasize the movement towards the G7, creating a sense of expectation and release.

Understanding the Difference

While both extended chords and secondary dominant chords play significant roles in harmonic structure, they serve different purposes. Extended chords are about adding additional notes to create a richer sound, whereas secondary dominant chords are about creating harmonic movement and tension.

Essentially, extended chords are about the what (additional notes), and secondary dominant chords are about the how (functionality and movement). This distinction is crucial for both composers and analysts to understand in order to effectively use these tools in their musical endeavors.

Key Takeaways:

Extended chords add additional thirds beyond the 7th, creating more complex structures. Secondary dominant chords act as temporary dominants, guiding the listener towards a different chord. Understanding both types of chords enhances musical composition and analysis.

Now that you have a better grasp of the differences between extended and secondary dominant chords, you can start incorporating these techniques into your own music. Happy composing and enjoy the rich harmonic landscape that these tools can offer!

Actionable Points:

Practice playing and composing with both extended and secondary dominant chords. Study additional examples in various musical genres to see how they are used. Experiment with these techniques in your own compositions to enhance their harmonic depth.

By combining these techniques, you can create a more dynamic and engaging musical experience for your listeners.