Basic Music Theory: How to Read, Write, and Understand Written Music

Basic Music Theory

Example 23.2 The harmonic intervals of a third and a seventh.

Interval Quality

In addition to having a number, each interval will also have a quality of

perfect, major, minor, diminished, or augmented.

In order to understand these qualities, we’ve got to take a look at the

major scale again. We’ll use the key of C Major because it’s the least

complicated, but these principles can be applied to any key signature.

Perfect Intervals

The Perfect intervals are: Unison (the same note, also called prime),

4ths, 5ths, and octaves (8ths). They’re called perfect because their sound

quality, which is a function of their vibration, which is mathematically

elegant. But let’s not get into the Golden Mean right now. For excellent

information on this subject, get Hearing and Written Music by Ron

Gorow.

The symbol for a perfect interval is “P”. So the intervals, when written

look like so:

See example 23.3 on page 200 for the perfect intervals in the C major

scale.

213

213

465

7

PU/PP perfect unison/perfect prime

P4 perfect fourth

P5 perfect fifth

P8 perfect octave