2.12 Modes and scales

Octave equivalence appears to be a universal feature of human hearing: Two sound frequencies related by a power of 2 are perceived as the same pitch. In Western music, we would give them the same “ letter name .” Thus, both of these pitches would be called the note “A.”

The half-step or semi-tone is the smallest melodic interval in Western music. It takes twelve half-steps to complete the octave.

Two half-steps create a whole step .

A scale is a pattern of steps rising from a tonic pitch. The Major scale ascends from the tonic in a fixed pattern of half and whole-steps:

Whereas a scale goes straight up and down, a mode uses the notes of the scale in any order. Music in the Major mode is based on the Major scale .

The Major scale may be transposed to any of the twelve notes of the chromatic scale. Here is a C-Major scale:

Here is a D-Major scale: It has same sequence of whole and half-steps, but starting on a different tonic .

This melody from Tchaikovsky’s Nutcracker Ballet travels down the Major scale .

The minor scale is more complex: It comes in three forms: natural, harmonic and melodic .

Thus, whereas the Major scale is always the same going up or down, the minor scale is more flexible, as shown in this cello solo from Franz Schubert’s Death and the Maiden.

No matter what the form of minor, one different remains constant: The third scale degree is always a half-step lower than in Major.

One half-step. It might not seem like much, but out of that one distinction, the full expressive richness of Common Practice music arises. This excerpt from Enrique Granados’ Andaluza turns on the fate of the third scale degree.

The modal conflict is particularly intense in Franz Schubert’s String Quartet No. 15 in G-Major. In the closing, Major and minor tonic chords engage in a tug-of-war. Who eventually wins?

The Major and minor scales are the basis of their respective modes. Any pitch may serve as tonic. Whereas the Major scale is uniform, the minor scale comes in three forms; this makes music in the minor mode more complicated.