Audio: mode (0:08)
mode plays modal scales on a harpsichord. The mode figure shows that each bar in the score consists of an ascending scale in one of the seven modes and the final bar is a melody in the aeolian mode. The mode table lists the names of each mode, the sequence of whole tones (T) and semitones (S), and an example scale.
The sequence of semitones and whole tones in each mode is unique. This is the defining feature of not just a mode, but of any scale. Every scale has a unique sequence of whole tones and semitones and no two scales share the same sequence. It is this unique sequence that gives each scale its distinctive sound.
Each mode contains five whole tones and two semitones. A whole tone is equal to two semitones. The total number of semitones always sums to twelve.
The seven modes are formed by starting on a different note in the sequence. For example, the sequence TSTTTST is the dorian mode. Starting on the next note results in the sequence, STTTSTT, which is the phrygian mode. Carry on like this and you get all seven modes: dorian, phrygian, lydian, mixolydian, aeolian, locrian and ionian.
The seven modes are derived from the first four pairs of intervals in Pythagorean tuning: unison and octave, fifth and fourth, second and seventh, and third and sixth. Rearranging them in order results in the sequence unison, second, third, fourth, fifth, sixth, seventh and octave, seven different notes plus the octave. Two of the modes, the dorian and the ionian, are shown in the third and sixth example.
Ionian mode is the same as the modern day major scale. It is the most widely used of the modes. Aeolian mode is the same as the natural minor scale and is one of three different types of minor scale. The other five modes have not disappeared. Locrian, dorian, phrygian, lydian and mixolydian are still there, just waiting to be used.
Mode is yet another of these words in music that looks simple at first sight yet turns out to have all sorts of meanings and a lot of historical baggage. The word is used in its modern sense, as outlined in this chapter.
You can use any mode to write melody or harmony. The ionian mode, or major scale, is very popular and is used a lot throughout the guide.