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What Are Diatonic Harmony and Roman Numerals

Understanding Diatonic Harmony: A Guide to Chords and Roman Numerals in Jazz.

If you're a musician looking to enhance your knowledge of jazz harmony, understanding diatonic harmony is a great place to start. In this comprehensive guide, we'll explore how diatonic harmony works, how chords are generated from a scale using only the notes of that one scale, and how the roman numeral system is used to label chords.

We'll begin by looking at triads and showing you how that system works. Triads are simply chords made up of three notes, and diatonic triads are chords generated from a scale using only the notes of that one scale. For example, we'll use the major scale in this article, which means we'll only be using seven notes and none of the black keys.

Once we've covered triads, we'll add sevenths to the chords, which will generate a lot of very common types of chords that you'll encounter when playing jazz standards. Adding sevenths to chords is crucial when building more complex chord progressions and harmonies.

The roman numeral system is a useful way to think about chords because it not only tells you what the notes of the chord are but also provides context for the chord and its function within that context. This is a very common device in jazz when discussing harmony, making it a concept that every aspiring jazz musician should understand.

By the end of this guide, you should have a solid grasp of diatonic harmony, the roman numeral system, and all the chords that are available to you from the major scale. We'll cover all 12 keys but don't worry, it's best to learn the theory and the system, which has a beautiful logic to it. Once you see the patterns and shapes, and understand why those notes are there, the whole thing becomes much easier.

It's worth noting that the chords along the top of the diatonic triads chart spell out the scale, which means we're starting on each note of the scale and building a chord on that note. The roman numerals underneath label the notes and follow the sequence of the degrees of the scale. For example, in the key of C major, chord one starts on the first degree of the scale and is a major triad. Chord two starts on the second degree of the scale and is a minor chord, and so on.

If you're new to jazz harmony, it can seem overwhelming to see all the chords and patterns laid out in front of you. However, by taking the time to understand the system, you'll find that it becomes much easier to learn and memorize.

This guide was created by Buster Birch, a professional musician and music teacher with over 30 years of experience. Buster has written and published many music tuition books for different instruments, which are available worldwide in print and for download. He also runs online workshops and courses and has many hours of video lessons available on his website, along with lots of free content on his YouTube channel.

In conclusion, understanding diatonic harmony and the roman numeral system is an essential part of learning jazz harmony. By taking the time to master this concept, you'll be well on your way to becoming a skilled jazz musician.

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