• Beyond the Number “Eight” – 4 Dimensions Of The Octave

    in Music & Children,Theory


    Octave comes from the Latin word octava, which means eight. Why is the number eight important in music? The number eight is important in music because it is the number of a new beginning. There are seven natural pitch-classes (A-G).

    A B C D E F G  octave

    If another pitch-class is added to the seven (A-G), we’ll have an A:
    A B C D E F G A octave

    And this takes us back to the pitch class we started (A). Therefore, the eighth or “octava” (octave) of a given tone is a higher (or lower) pitch-level of that same note.

    Octave of A is A:
    A - A

    Octave of B is B:
    B - B

    Octave of C is C:
    C - C

    Octave of C♯ is C♯:
    C sharp - C sharp

    There are occasions when the octave can be used to refer to a note that is an eight lower than a given note. This is called Octava Bassa, which means low octave (we’ll get to that).

    So far, this is just a layman’s understanding. Let’s look at something that is beyond the obvious association of octave with the number eight.


    There’s a scientific relationship between a note and its octave. In physics and acoustics, when any pipe is blown, it produces a pitch (aka – “note”) and this pitch is called the fundamental tone

    It is called a fundamental tone because when the pipe is over-blown, it produces other notes called harmonics or upper-partials. The very first upper-partial is the octave. The octave of any fundamental tone is its upper-partial. Upper partials are also perceptible on the piano. However, it takes gifted hearing.

    If you play the lowest A on an acoustic piano with its octave, it sounds muddy. This is because of the super-imposition of the upper-partial of the fundamental tone and the octave. As you move to higher registers (don’t worry! I’ll explain registration shortly), upper-partials are less perceptible.


    There are so many ways the term octave can be used. It could mean one thing in a given context and another thing in a different context. 

    #1 – DISTANCE

    Octave is the distance of an eighth from a given note. In this usage, it refers to a note with the same pitch class whose distance is an eighth higher or lower than the given note. The octave of a given note, let’s say C, is the next C on the keyboard. Most times, it refers to the higher eighth.

    E.g. – C-E. 

    Instruction: Play the E note an octave higher:

    C E

    In this context, C Major third (played as C-E):

    C E

    will look like this:
    C octave E


    There are also occasions where octave means the lower eighth. In such situations, the reverse will be the case.

    Consider this C-E interval (which happens to be a compound interval [a bigger variation of the regular C-E]):

    C E

    Instruction: Play the E note an octave lower.

    In this context, C Major tenth (given as C-E):

    C octave E

    will look like this:
    C E

    This is the binding principle of Octave Transposition. We’ll talk more about this shortly.


    #2 – DUPLICATE

    Octave is duplication of a given note by a higher or lower eighth. It can be seen as harmony – that means the relationship between the first tone and the eighth tone of a series, sounded together.

    E.g. – F 

    Instruction: Play the F note in octaves. 

    In this context, the F note (which was given as):


    will look like this:

    F octave F

    This is the binding principle of Reinforcement. We will cover it shortly.


    #3 – REGISTER

    Octave is the aggregate of all the notes within its compass.

    E.g. – within the compass of C:

    C octave C

    We can have the following notes as an octave. This is true because all the notes are within the compass of one octave.
    All notes within C octave

    All the notes below can be referred to as an octave. They are within its compass.

    Octave of E

    All notes within E octave

    Octave of A

    All notes within A octave

    This is the binding principle of Registration. We’ll talk more about this shortly.


    An octave can be symbolized. The symbol is derived by using the numerical value of the octave, which is 8 and two alphabets in superscript. 

    Below are the symbols for an octave, where they’re derived from, and what they mean.

    8va        – Octava                      –           An Octave higher

    8vb          – Octava Bassa           –           An Octave lower


    Two Octaves

    Most times, two octaves can also be symbolized. If the notes within the span of two octaves is written out and numbered, it would look like this:

    C D E F G A B C D E F G A B C

    C D E F G A B C D E F G A B C
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

    There you have it – a span of FIFTEEN notes. The distance of two octaves is a fifteenth and is called a Quindicesima in Italian. Alright! Pronounce it slowly and syllabically:


    After pronouncing this word slowly as “Quin|di|ce|si|ma,” you’ll get more comfortable with adding it to your musical vocabulary.

    However, still say “two octaves” when you can. There are so many people out there who know what two octaves are but don’t know what a Quindicesima is. Also, learn when you have to sound professional and when it’s unnecessary (which is most of the time). :-)

    *User’s discretion advised.

    Just like the octave, the Quindicesima has its symbol too. The process of deriving the symbol is also similar. Here are the symbols of the Quindicesima.

    15ma      – Quindicesima            –           Two Octaves [a fifteenth] higher

    15mb     – Quindicesima Bassa  –           Two Octaves [a fifteenth] lower

    Now, we’re done with the definition, usage and symbolization of the octave, let’s delve into four dimensions of the octave.



    Transposition can be broke down into Transfer of Position. Melodies can be transferred from a lower register to a higher register or vice-versa for effect, range or even convenience.

    For Effect: You’ve seen musicians and singers start songs an octave lower than the actual register they intend to sing in. While everyone is wondering what’s going on, they take it an octave higher into another register. This creates a beautiful effect that has always got the audience clapping. If you’re a fan of Kirk Whalum or Whitney Houston, etc., then you have surely experienced the octave effect.

    For Range: There are 88 keys on the piano. There are certain keyboards out there that do not have 88 keys. We have 61-key keyboards, 76-key keyboards, etc. And there are situations where the keyboardist will have to use the octave transposition function on the keyboard to make the keyboard sound an octave higher or lower. If you are an experienced player, you’ll agree with me that there are occasions when you’ve played a keyboard that is transposed. Did you notice it sounded lower or higher than usual? That’s what octave transposition does. It can electronically increase the range of an instrument. For acoustic instruments that can’t transpose their octave electronically, they’ll have to be played at their convenient register.

    For Convenience: If a soprano saxophonist and a bassist (who is using a 4-string bass) are playing a particular melody. Note that the instruments in question are named after their range and this means that their range is limited to the register they can produce. The truth remains that there are certain high pitches the bass cannot produce that the soprano saxophonist can produce easily. There are also low pitches the bass can produce that it is impossible for the soprano sax to produce. Therefore, each instrument will have to play at their convenient register. This leads to a dynamic contrast. Remember that when a musical idea is played in octaves, it is reinforced.

    This is the dimension of distance.


    Octaves connect notes that have the same letter name but vary in pitch-level. With this, you can make an idea come out bolder by emphasizing it with octaves. Most times, when you want a particular note to come out bolder, the best thing to add is not other tones of the scale; the best thing to do is to duplicate that note by adding its octave. With that, the note sounds reinforced.

    Scales: When scales are played with both hands 8va or 15ma apart, they sound reinforced. Classically trained musicians practice and master this.

    Melodic Figures: Beyond scales, other melodic figures like licks, phrases, arpeggios, runs and scale fragments sound reinforced when played with both hands. Richard Smallwood actually does such reinforcements and it’s a good thing to emulate.

    Chords: Harmonic structures aren’t left out. When a triad is played in octave position, it sounds better. A triad can be played in octave position by duplicating its outer notes. E.g. C-E-G, which is the root position of C Major triad, can be played in octave position by the duplication of C. With that, you’ll have C-E-G-C.

    C-E-G-C – The outer Cs in this octave position reinforces this triad and makes it sound fuller.

    Right-hand melodies and left-hand bass lines can be reinforced using octaves. Most times, we prefer playing octaves on the left-hand to playing just a note. We all love our notes reinforced and the octave is the right sanctuary for reinforcement.

    Octave is used here as a duplicate


    Octaves help us classify pitches according to registers – lower and higher registers. Octaves to the left constitute what we call the lower register while octaves to the right are called higher registers.

    Below are the registers of an 88-key keyboard or Acoustic Piano:

    • From the first C to the second B is the Contra Octave
    • From the second C to the third B is the Great Octave
    • From the third C to the fourth B is the Small Octave
    • From the fourth C (aka – “middle C”) to the fifth B is called One Line
    • From the fifth C to the sixth B is called Two Line
    • From the sixth C to the seventh B is called Three Line
    • From the seventh C to the eighth B is called Four Line

    Not all keyboards have this range. The 61-key keyboard below has the following registers:

    • From the first C to the first B is the Great Octave
    • From the second C to the second B is the Small Octave
    • From the third C (aka middle C) to the third B is called One Line
    • From the fourth C to the fourth B is called Two Line
    • From the fifth C to the fifth B is called Three Line

    And that’s about five octaves.

    The use of octave here is as a register.


    Octave also comes into the picture during the process of inversion. This is called the octave transposition technique. Here, the lowest note can be played an octave higher or the highest note played an octave lower.


    Intervals: C-E is a Major third
    C E major third

    1. (Heck! I love using Major thirds a lot. If you want to know why, check out this lesson on consonant intervals).

    Inversion of this interval can be done using the octave transposition technique:

    C is the lower note and should be played an octave higher. Therefore 8va of C will yield E-C.
    E C


    E is the higher note and should be played an octave lower. Therefore 8vb of E will also yield E-C.
    E C

    The inversion of any interval follows this process.

    Chords: C-E-G is the most common Major triad.
    C E G

    It can be inverted using the octave transposition technique.

    C is the lowest note in root position (C E G) and should be played an octave higher. Therefore 8va of C will yield E-G-C.
    E G C


    G is the highest note in root position (C E G) and should be played an octave lower. Therefore 8vb of G will yield G-C-E.
    G C E

    The inversion of all triads and seventh chords follows this process.

    The use of octave here is similar to the that of octave transposition.
    Now you know that there’s more to an octave than an eighth.


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    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.


    { 1 comment… read it below or add one }

    1 Dennis david

    I find your lessons very informative.sorry I did not sign up. Keep up the good work and thanks for being patient


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