• A Lesson On The Four Known Qualities Of Third Intervals

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    In today’s lesson, we’ll be taking a look at four known qualities of third intervals.

    Although intervals are the building blocks of chords, third intervals are mostly used in chord formation in classical, jazz, and other music styles. Chords that are built of third intervals are said to have tertian harmony.

    Due to the importance of third intervals in chord formation, it is important for every serious musician to be familiar with all qualities of third intervals, and that’s our goal in this lesson. But before we go into all of that, let’s take a look at intervals.

    A Short Note On Third Intervals

    An interval can be defined as the relationship between two notes in terms of the distance between them.

    The above definition has all the vital keywords that can paint a picture of what an interval is..

    • Relationship
    • Two notes
    • Distance

    …however, it is important for us to highlight them.

    “The Relationship…”

    An interval is the relationship between notes. In a previous lesson on note relationships, we covered two relationships – melody and harmony.

    Melody is the relationship between notes that are heard separately while harmony is the relationship between notes that are heard at the same time. The two types of note relationship (melody and harmony) influences the two kinds of intervals – melodic and harmonic intervals.

    A melodic interval is an interval where the notes are heard separately, while a harmonic interval is an interval where the notes are heard separately while a harmonic interval is an interval where the notes are heard at the same time.

    “Two Notes…”

    On of the properties of an interval is that it is has two notes. The relationship between three or more notes are considered as chords. The following:

    C and B:

    A and Db:

    …are intervals, while the following:

    C, E, and G:

    F, Ab, and Cb:

    …are not.


    Intervals can also be used to describe the distance in pitch between notes. The distance between C and A:

    …is a sixth because the interval C-A encompasses six degrees of the C major scale:

    …from C to A:

    “What Are Third Intervals?”

    A third interval is any interval that encompasses three letter names.

    In the C major scale:


    …is a third interval because it encompasses C, D, and E:

    …three letter names. There are several other third intervals in this scale.

    “Check Them Out…”


    …encompassing three letter names (D, E, and F):


    …encompassing three letter names (G, A, and B):


    …encompassing three letter names (B, C, and D):

    Third intervals are considered to be important because they are mostly used in the formation of tertian chords. Chords like the C major ninth:

    …contains several third intervals like C-E:



    …and B-D:

    Due to their importance, we’ll be exploring four qualities of third intervals in the next segment.

    Four Known Qualities Of Third Intervals

    The term third does not state the exact size of an interval. For example, C-E:

    …and D-F:

    …are all third intervals, however, they have different sizes. C and E:

    …contains four half steps while D and F:

    …contains three half steps.

    Due to the fact that the use of the term “third” does not state the exact number of half steps a third interval contains, certain adjectives are used to describe and qualify various sizes of third intervals.

    “Check Out These Sizes Of Third Intervals…”

    #1 – The Diminished Third

    The third interval with the smallest number of half steps is the diminished third interval and it contains two half steps. These intervals below…

    D# and F:

    E and Gb:

    A# and C:

    B and Db:

    …are diminished third intervals and encompass the distance of two half steps each.

    #2 – The Minor Third

    The minor third interval is a product of the relationship between the first and third tones of the minor scale and encompasses a distance of three half steps. Here are some of them below…

    D and F:

    E and G:

    A and C:

    B and D:

    #3 – The Major Third

    The relationship between the first and third tones of the major scale produces the major third interval. The major third interval encompasses a distance of three scale steps in the major scale. Check them out…

    D and F#:

    E and G#:

    A and C#:

    B and D#:

    #4 – The Augmented Third

    The augmented third interval has the biggest width – encompassing five half steps. Below are a few examples…

    Db and F#:

    Eb and G#:

    Ab and C#:

    Bb and D#:

    …encompassing five half steps.

    “In a nutshell…”

    All third intervals are not equal. The intervals below…

    • D# and F
    • D and F
    • D and F#
    • Db and F#

    …are all third intervals because they encompass three letter names from D to F, however, playing them on the piano shows their difference in size.

    D# and F:

    …is a diminished third.

    D and F:

    …is a minor third.

    D and F#:

    …is a major third.

    Db and F#:

    …is an augmented third.

    Consonant vs Dissonant Thirds

    There are basically two classes of third intervals – consonant and dissonant thirds.

    The term ‘consonant’ is used to describe a collection of two or more notes that sound pleasant and agreeable when played together, while the term ‘dissonant’ is used to describe a collection of notes that are unpleasant and harsh.

    Major and minor third intervals are classified as consonant intervals while augmented and diminished intervals are classified as dissonant intervals. Major and minor third intervals are used in the formation of tertian chords, while augmented and diminished third intervals are rarely used.

    Here’s a breakdown of the intervals in the C major ninth chord:


    …a major third.


    …a minor third.


    …a major third.


    …a minor third.

    Even diminished chords that are considered to be dissonant, can be broken down into consonant intervals. For example, the G# diminished seventh chord:


    …a minor third.


    …a minor third.


    …a minor third.

    You’ll hardly come across the augmented and diminished third intervals in the formation of tertian chords.

    Final Words

    Although there are three known qualities of the interval, the major and minor intervals are commonly used. Therefore, it is important for you to learn and master them in all twelve keys.

    “Here you are…”

    Major Third Intervals

    C major third:

    Db major third:

    D major third:

    Eb major third:

    E major third:

    F major third:

    F# major third:

    G major third:

    Ab major third:

    A major third:

    Bb major third:

    B major third:

    Minor Third Intervals

    C minor third:

    C# minor third:

    D minor third:

    Eb minor third:

    E minor third:

    F minor third:

    F# minor third:

    G minor third:

    G# minor third:

    A minor third:

    Bb minor third:

    B minor third:

    Thanks for your time and see you in another lesson.

    The following two tabs change content below.
    Onyemachi "Onye" Chuku (aka - "Dr. Pokey") is a Nigerian musicologist, pianist, and author. Inspired by his role model (Jermaine Griggs) who has become his mentor, what he started off as teaching musicians in his Aba-Nigeria neighborhood in April 2005 eventually morphed into an international career that has helped hundreds of thousands of musicians all around the world. Onye lives in Dubai and is currently the Head of Education at HearandPlay Music Group and the music consultant of the Gospel Music Training Center, all in California, USA.

    Attention: To learn more about this, I recommend our 500+ page course: The "Official Guide To Piano Playing." Click here for more information.


    { 3 comments… read them below or add one }

    1 Joe

    Great lesson Dr. Pokey.


    2 sr. sofia roferes

    Dr. Pokey, thank you so much. the lesson is of great help for my initial studies to learn piano. God bless you and your ministry.


    3 Chuku Onyemachi

    Amen! God bless you too.


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