A single note played on an instrument can generate enough harmonic over-
tones to define an entire scale. Harmonic overtoneshappen whenever you
play or sing a note. For example, when you play an open A string on the
guitar, the string vibrates along its entire length, but it also makes smaller
vibrations along two equal halves of its length, three equal thirds, and so on.
Each of these smaller vibrating subdivisions of the string produce pitches
that are related harmonically and mathematically to the fundamental A that
you are playing. We hear these overtones as part of the timbreof the instru-
ment, and don’t usually think of them as separate pitches — but that A you
play actually generates (albeit quietly) all the pitches of the A major scale
and beyond. This is why a brass instrument like a trumpet can play so many
different pitches with only eight possible valve combinations, which relate to
tubing lengths.Added to this is the fact that it is quite possible (if not likely) that the melody
in your head is already diatonic,meaning that it has a key center (making it a
tonal melodyas opposed to an atonal one). This means that there is a particu-
lar musical scale or set of related pitches from which your melody is drawn,
or with which your melody will feel conformable. This has to do with the way
in which our ears work, along with the musical exposure to scales and modes
that you may have had.So, without our realizing it, tonal melodies do tend to make their own
demands regarding harmony. You just have to be paying attention and have
the proper tools at hand, such as a pencil and paper or a keyboard and com-
puter, to capture what you hear in your head.Harmony in music can be defined as any combination of notes that are played
together at the same time. If you play a C and a G together, they sound pleas-
ant, or consonant (Figure 9-1).&4
4
w
w
Figure 9-1:
C and G are
consonant
because
they are
a perfect
fifth apart.