Music Theory

[last updated: 2026-09-16]
Disclaimers
Scales
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ROUGH, INCOMPLETE, EDIT IN PROCESS......

• Foundation:
  You can think of music theory as being based on a standard piano keyboard.
  • A standard keyboard has 88 keys:
    • The term 'key' has multiple meanings.
      This is the first meaning, and designates a physical element, plastic or ivory, either white or black, that you press to create a sound.
    • Keys are named:
      • White keys are named a letter from A to G (..., then repeating, starting over with A for the next white key as you go up the keyboard,)
      • Black keys are named in reference to whichever white key they're closest to.
        Since black keys always are between two white keys, there are two alternative names that can be applied to each black key.
        ...Then an additional character is added to the key's name to denote whether the black key is up, higher pitch, or down, lower pitch, from its reference key,
        • If the black key is higher pitch than its reference key, it is called a "sharp."
          A symbol is used when you want to refer to a 'sharp', so you don't have to spell out the whole word:
          '#'
        • If the black key being named is lower pitch than its reference white key, it is called a "flat."
          The symbol used to denote a flat is:
          '♭'

  • A "note" or sound is produced when you strike a key on the piano.
    The note/sound produced when you strike a key has a given frequency or pitch.
    For example, the A above middle C on the keyboard (also designated A4) produces a frequency of 440 Hz.
    This note has been designated as an international standard that musicians and orchestras use to tune their instruments.
  • Octaves:
    • An octave is a set of 12 sequential keys/notes, including all white and black keys until you return to the starting note.
      [insert image here]
    • The frequency/pitch of a given note is exactly half the pitch of the same-named note 1 octave higher.

  • Semitones:
    • Semitones are a measure of distance between two notes.
      Two notes on the keyboard that are right next to each other,
      that is, there are no other notes, either white or black, in between them,
      are said to be "1 semitone apart."
    • So for example, there is 1 semitone between a C and a C#,
      and there are two semitones between a C and a D.

    • Semitones are used in several different ways in musical composition.
      For example, a "perfect 5th" is two notes separated by 7 semitones.
          This relationship is true regardless of what key you are in.

    • Semitone patterns for constructing a scale:
      If, for example, you start with the C-major scale,
          C, D, E, F, G, A, B
      and count the number of semitones between the notes,
      you get this sequence (starting from the distance between C & D, ending with the distance between B and the next octave C):
          2, 2, 1, 2, 2, 2, 1
      By definition: all major scales, regardless of key/tonic,
      have this same pattern of semitone intervals between notes.

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