Scales and the Overtone Series

     A musical scale is basically a collection of notes that divide the octave in a certain number of scale steps. The reason why the pitches are organized within one octave is so we can proceed with the same notes or scale formation throughout the other octaves. In effect, this means that we can devise our own scales according to a given musical intent but for now we will begin by looking at the most commonly used group of scales and their respective modes.

     Looking closely at the overtone series, we can easily gather a collection of notes that span the octave. For instance:

Put in order, we get:

     This is a pentatonic scale (a group of five sounds within the octave). Considering that it derives from a natural phenomenon, that should explain why it is present in the music of many and different cultures around the world. Even today, it is one of the most used scales be it in Pop, Rock, Blues, Jazz, you name it.

     We can make other extrapolations from the series, like a scale that is referred to as the acoustic or overtone scale – aptly named from its source material. In Western Music tempered tuning system it is also known as the Lydian ♭7, the fourth mode of the melodic minor scale. This scale is an approximation of the extrapolation below:

Put in order, and compared to the Lydian ♭7 scale, we get:

The only note that differs from the Lydian ♭7, in this case, is the G#

     As seen in the previously example, many of the acoustic observations might not exactly translate to the tempered tuning system. For instance, the 7th partial of the overtone series is not exactly a B♭ – this naturally occurring frequency does not match with the B♭ in the 12-tone tempered tuning system, however close. Nevertheless, this material is invaluable when mixed with a composer’s artistic vision.

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