Introduction to Intervals

The distance between two notes is called an interval, and it is measured by counting the number of degrees between them within a certain key. For example, in the key of D, going from D to F# is a third interval.

Intervals can be further classified based on the relationship between whole and half steps, and can be described as major, minor, perfect, augmented, or diminished. Here is a summary of all intervals based on the key of C:

Unison: C to itself

Major second: One whole step above C, which is D

Minor second: One half step above C, which is Db

Major third: Two whole steps above C, which is E

Minor third: One whole step and one half step above C, which is Eb

Perfect fourth: Two whole steps and one half step above C, which is F

Augmented fourth: Three whole steps above C, which is F#

Diminished fifth: Three whole steps above C, which is Gb

Perfect fifth: Three whole steps and one half step above C, which is G

Augmented fifth: Four whole steps above C, which is G#

Minor sixth: Four whole steps and one half step above C, which is Ab

Major sixth: Four whole steps and two half steps above C, which is A

Minor seventh: Five whole steps above C, which is Bb

Major seventh: Five whole steps and one half step above C, which is B

Based on this classification, intervals of second, third, sixth, and seventh are only classified as major or minor, while intervals of fourth and fifth are classified as perfect, augmented, or diminished. It is worth noting that a diminished fourth is equivalent to a major third, and an augmented fourth is equivalent to a diminished fifth, which is almost always referred to as such.

When practicing interval recognition, it may be difficult to directly calculate intervals larger than a fourth. However, perfect fourth and perfect fifth are relatively easy to remember, so it is recommended to memorize them. For intervals larger than a fifth, the reverse calculation method is recommended, where you use the compensation relationship between intervals to calculate the larger interval based on the smaller one.

For example:

From C, counting down a minor third will give you A, while counting up a major sixth will also give you A

From C, counting up a major second will give you Bb, while counting down a minor seventh will also give you Bb

This relationship between intervals follows a pattern:

Second ↔ Seventh, Third ↔ Sixth, Fourth ↔ Fifth

Major ↔ Minor, Augmented ↔ Diminished, Perfect ↔ Perfect

Here are some examples of compensating intervals:

Minor third ↔ Major sixth, Perfect fifth ↔ Perfect fourth, Augmented fourth ↔ Diminished fifth

It is important to note that the augmented fourth and diminished fifth compensate each other and are equivalent. This interval is also important and should be memorized.

Apart from knowing how to calculate intervals, it is also important to recognize how they sound. Ultimately, our ears are the most important judges of music. Additionally, the examples given in this article are based on the key of C, so it is recommended to practice recognizing intervals from different starting notes and in different directions to fully understand the relationship between notes.

by < Daniel Chen >

- Guitar Teacher of Fusian Music

- Graduated from Berklee College of Music

- See more in Fusian Music Website