Intervals

An interval is the distance between 2 notes.

Most good melodies contain a variety of intervals, ie. the distance and the direction between succeeding notes will vary.

Some notes repeat.
Some notes move up of different distances.
Some notes move down of different distances.

How do we label these distances?
Intervals -- numbers which define their distance.

There are large intervals.
There are small intervals.

Intervals beyond an octave are called compound intervals.
The largest interval is a 13th.

Intervals within an octave range from a 2nd to a 7th.

The number of keys within an octave -- 12.
How can 7 interval numbers account for 12 notes?
The answer is that intervals can have different qualities.

For eg.

C to G -- 5ths
C to Gb -- 5ths
C to G# -- 5ths

All of these are 5ths.


The most common intervals are 2nds.
This is the case with most good melodies.
When the melody proceeds by 2nds, it is said to be moving step-wise.

But too much step wise movement will tend to get boring.

Compound intervals in vocal melodies are rare cuz of their awkwardness for singing.
But they are important for harmony.


Inversions

There is also 'flip-flop'.
Take the 3rd: F to A.
If you take the F and move it up an octave, what happens to the interval?
If you take the A and move it down an octave, what happens to the interval?

It becomes a 6th.

Notice the sum of 3rd + 6th = 9.

Try this with other intervals (up to an octave) and the same thing will happen.

Flip-flopping is called inversion.
This is imp concept when we build our chords.