In previous modules we learned that scales are constructed from whole steps and
half steps, in Western music, whole steps and half steps forming scales
are the building blocks of tonality, although jazz styles use altered notes
called blue notes that fall between half steps, which we won't discuss here.
We said that the term half step is a description of the sound created
by playing two adjacent notes on a piano, white key to black key, or
white key to white key when there is no black key between them.
Or two adjacent frets on a fretted instrument, so here's a half step.
[SOUND] A whole step is equivalent to two half steps or two notes on a piano,
or a fretted instrument that have a note between them.
[SOUND] There's a whole step.
Because the terms half step and whole step describe sounds,
it doesn't matter how they are notated, we can use any enharmonic spelling we like.
So, for example, these two notes on the piano [SOUND] form a half step,
regardless how they are spelled.
The notes could be called E and F.
[SOUND] E and E sharp.
[SOUND] F flat and F.
[SOUND] Even E and G double flat.
All of these spellings produce the same sounding notes which form the sounding
interval called a half step, but when we start working with scales, and keys,
and notated music, the spellings of notes do make a difference.
In C major, the key with no sharps or flats,
the diatonic spelling of these two notes [SOUND] is E and F.
In addition to describing the sound as a half step, we have a precise way of
labeling this half step based on the spelling of the notes that form it.
In this size quality labeling system, we refer to the so-called generic
size of the interval with a number, such as a 2nd or a 3rd, to which we
add a quality label such as major, minor, perfect, diminished or augmented.
The size label is based on notes spelling and
the quality label is based on the number of half steps.
Let's talk about the size label, the interval between a note and
itself, or another note with the same note letter name but a different accidental,
would be called a 1st, except that we traditionally refer to it as a unison.
A note to the note with the next letter name such as C to D is a second,
and so on, up to the interval between low C and high C, which is an 8th,
which we typically call an octave.
Notice that a second is the interval between notes that are separated by
one notated letter names, such as E to F or
A to B, regardless of what they sound like and regardless of accidentals, so
this E to F is a second, as is this E flat to F.