What does mode mean in musical terms?

Answer 1

In its basic form, a mode is the basic form of a scale starting from any white key, going to the white key an octave above or below, only including the white notes in between. There are seven basic modes according to this definition, simply because there are seven unique white keys. This is only one way of defining modes, and in reality some more obscure modes use tones that are not necessarily restricted to the western equal temperament, the system enthusiastically embraced and advanced by composers like J. S. Bach.

The most commonly used modes are the diatonic modes. Taking a root note of C as the base note for the first, and going up the C scale to compare modes, these are the following:

• Ionian (tonic) (starting on C)
• Dorian (supertonic) (starting on D)
• Phrygian (mediant) (starting on E)
• Lydian (subdominant) (starting on F)
• Mixolydian (dominant) (starting on G)
• Aeolian (submediant) (starting on A)
• Locrian (leading note) (starting on B)

Modes can be transposed up or down as many as 11 semitones, and as long as the intervals remain the same, it is still modal. For example, "Scarborough Fair" is written in dorian mode, but is often translated to what sounds, to modern Western music ears, like E minor. This follows the very same idea that there are 12 unique major scales, assuming the equal temperament equivalence of keys like F sharp and G flat.

When you think about it, when you build the modes in this way using the white keys of the standard keyboard, the difference between any two modes is the location of the half steps (or semi-tone steps). The actual distance between the half stepsis always the same. They happen between B and C, and between E and F. This is why the modes are called 'diatonic'; they are all built on the basic structure of the diatonic scale. Starting on any key, the major diatonic scale (Ionian) is built by going up: T, T, s, T, T, T, s where T is a tone (whole step), and s is a semitone (half-step). This algorithm brings you from any key to the key an octave above. This is also why modes are easily transposed. They are not based on absolute pitch, but upon the steps used to build them. Another way of viewing the diatonic structure of the major scale is as two basic units (T, T, s) separated by a Tone (F-G in the key of C major).

While there are practical uses for most modes, the Locrian mode is, to Western ears, the most awkward, perhaps because it is the only mode whose tonic triad (B natural, D natural, F natural in this case) is a diminished chord; the fifth is diminished. All others would be major or minor, and their fifths are perfect.

Examples of notable modern pieces composed in modes include: "Smoke on the Water" by Deep Purple (dorian mode), and, as an example of something written in the rarest, the march in the Shostakovich set "Three Fantastic Dances" is written in Locrian mode.

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