Interval Identification // Perfect Eighths And Octaves (8 of 10)
Run time: 2m 56s | Release Date: March 25th, 2020
Section 1 - "Definition"
An interval of a Perfect eighth, also known as an octave, is an interval in which two notes of equal letter name are sounded at double, or half, the vibrational frequency of each other. For example, if a note vibrates at a frequency of approximately 440 hertz, or 440 cycles per second, then an octave above that note will vibrate at a frequency of approximately 880 cycles per second while an octave below that note vibrates at a frequency of about 220 cycles per second.
Section 2 - "Amount of Steps"
The amount of steps in between any two pitches which produces an interval of a Perfect eighth is any combination of steps equalling twelve consecutive half steps.
Section 3 - "How To Read On The Staff"
Because of the amount of steps separating each note, identifying an interval of a Perfect eighth on the staff can be a bit tricky. However, you will notice that if the bottom note of the octave is on a line then the top note will always be found on a space with three lines and three spaces between them. And if the bottom note is on a space then the top note will be found on a line with three spaces and three lines between them.
However, the easiest way to identify this interval would be to simply read the letter name of each note. If the letter names are the same then you will know that the interval is a Perfect eighth, or octave. For more information on note identification, click on the link in the description below.
Section 4 - "Relation To The Scale"
In previous videos in which we discussed an interval of a Perfect fourth and an interval of a Perfect fifth we learned that any interval which is considered Perfect is always the same note position on both a Major and minor scale.
This applies to an interval of a Perfect eighth as well. An interval of a Perfect eighth is simply the root note found after the seventh scale degree of that note's Major or minor scale.
Section 5 - "Example In Music"
An example of an interval of a Perfect eighth played melodically in a popular piece of music occurs between the first and second notes of "Somewhere Over The Rainbow". Do you know any other examples of an interval of a Perfect eighth, or octave, in a piece of music? If so, comment below and share!
Section 6 - "Wrap Up"
Now that we have covered all of the basic intervals, in the next video we are going to discuss diminished and augmented intervals. We will be introduced to a tritone and understand how it pertains to the tension and resolution of a Dominant chord.
A diminished interval occurs when a minor or Perfect interval is flattened by one half step. For example, in video seven of this series we learned that, because the two notes are separated by ten consecutive half steps, an interval of a minor seventh above the note A is the note G. Knowing that a diminished interval is created when a minor interval is flattened by a half step, if an interval of a minor seventh above A is G, then an interval of a diminished seventh above A would be the note G-flat.
Now, the note G-flat is the enharmonic equivalent of the note F-sharp, meaning both letter names are in fact the same pitch.