Octaves and scale formation

Side Note

As you read this apply what you have learned to any instruments you have at your disposal. Things fall into place once you put them into practice.

Octaves

When you play an ocarina the air entering and leaving the chamber pushes on the air in your environment. This causes waves to travel trough the air much like those on the surface of a pond. When they reach your ears you hear a sound.

These waves can be visualized as a graph. High points represent pressure fronts and the low points represent the low pressure regions between them.

All waves have a frequency, the number of peaks that pass a point in space in 1 second. When two notes sound and one is exactly double the frequency of the other the human mind perceives both with the same tone. This is called an octave. Incidentally the phenomenon is not limited to a single doubling. If the high wave is again doubled, now 4 times the frequency of the first, all 3 are perceived equivalently. The following animation demonstrates the idea:

Because of this the notes used in music actually repeat. This repartition exists on all instruments but is most obvious on the piano keyboard. Western music divides the octave into 12 notes, 12 sequential white and black keys. After note 12, it returns to note 1 an octave higher or double the frequency.

The keyboard simply repeats these same 12 notes from left to right. This grouping can be identified easily by looking at the black keys, which are grouped into twos and threes.

If you pick any note within one octave and play a tune, then play the same sequence from that key in a different octave it will sound like the same tune. You can also play a sequence in two or more octaves at the same time. When a note sounds in multiple octaves the highest is heard as the melody and the lower ones create a richer tone.

As the frequency of a sound is determined only by it's peaks the shape of the wave in between can vary. These differences are perceived as tone colour or timbre. It is what enables you to distinguish one instrument from another.

Scales used in music

As mentioned above each octave contains 12 notes. From this point on things are easier to understand if the notes are simply considered in a line. The distance or 'interval' between any two of these notes in sequence is called a half step or semitone. note 1 to note 2 is a half step, Note 2 to note 3 is also a half step and so on.

And from G, notice that this sounds much the same despite starting on a different note:

Thoughts on...

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