Chapter 2:Intervals 21
Major and Minor Intervals
When you describe intervals by degree, you still have to deal with those pitches
that fall above or below the basic notes—the sharps and flats, or the black keys
on a keyboard.
When measuring by degrees, you see that the second, third, sixth, and seventh
notes can be easily flattened. When you flatten one of these notes, you create
what is called a minorinterval. The natural state of these intervals (in a major
scale) is called a major interval.
Here’s what these four intervals look like, with C as the root, in both major and
minor forms.
Major and minor intervals, starting on C.
Perfect Intervals
Certain intervals don’t have separate major or minor states (although they can
still be flattened or sharpened). These intervals—fourths, fifths, and octaves—
exist in one form only, called a perfect interval. You can’t lower these intervals to
make them minor or raise them to make them major; there’s no such thing as a
minor fifth or a major octave. The intervals, because of their acoustical proper-
ties, are perfect as-is.
Remember, in this chapter
we’re dealing with inter-
vals within a major scale.
Minor scales (described in
Chapter 3) have different
“natural” intervals between
degrees of the scale.NoteWhy is a perfect interval so perfect? It all has to do with frequencies, and with
ratios between frequencies. In a nutshell, perfect intervals sound so closely related
because their frequencies are closely related.
For example, a perfect octave has a ratio of 2:1 between the two frequencies—
the octave is twice the frequency of the starting pitch (which is called the funda-
mental). If the fundamental is 440Hz, the octave above is twice that frequency,
or 880Hz. Similarly, a perfect fifth has a ratio of 3:2, and a perfect fourth has a
ratio of 4:3. Other intervals have more complex ratios, which makes them less
perfect. For example, a perfect third has a ratio of 5:4, not quite as simple—or
as perfect.
Put into a series, each increasingly complex interval ratio forms what is called a
harmonic series,and the intervals (in order) are called harmonics.But don’t get
hung up on all the math; what’s important is that you know what the perfect inter-
vals are, not the math behind them.Note