Theory is a language, and like any language it starts with vocabulary. This chapter is the reference for the terms used across the rest of the module. You do not need to memorise it all at once - come back to it whenever a word stops making sense.
Pitch, notes and octaves
- Pitch is how high or low a sound is, determined by its frequency. A4 - the A above middle C - is the standard tuning reference at 440 Hz.
- Notes are the named pitches. Western music uses twelve, repeating in every octave.
- An octave is the distance between one note and the next note with the same name - double the frequency. A3 is 220 Hz, A4 440 Hz, A5 880 Hz.
- Middle C is the C near the centre of a piano keyboard. DAWs disagree on what to call it - C3 in some, C4 in others - so check yours when following instructions.
Naturals and accidentals
- Naturals are the white keys on a piano: A, B, C, D, E, F, G.
- Accidentals raise or lower a note. A sharp (#) raises a note by a semitone; a flat (b) lowers it by a semitone. A natural sign cancels a previous sharp or flat.
- The black keys are the sharps and flats.
Enharmonic equivalents
The same pitch can have two names. C# and Db are the same key on a piano - they are enharmonic equivalents. Which name you use depends on the key: in D major you write F# and C#; in Ab major you write Db and Eb. The rule is that each letter name appears once in a scale, so the name changes to keep that true.
There are also two pairs of white keys with no black key between them: E-F and B-C. That is why E# is the same pitch as F, and Cb the same as B.
Tones and semitones
- A semitone (half step) is the smallest distance in Western music - one key to the very next, black or white. C to C#, E to F.
- A tone (whole step) is two semitones. C to D, E to F#.
Scales are defined by their pattern of tones and semitones, written W (whole) and H (half). The major scale is W-W-H-W-W-W-H.
Intervals
An interval is the distance between two notes, named by counting letter names and then qualified by its exact size.
- Unison - same note (0 semitones).
- Minor 2nd - 1 semitone. Tense, crunchy.
- Major 2nd - 2. Open, mildly tense.
- Minor 3rd - 3. The sound of a minor chord.
- Major 3rd - 4. The sound of a major chord.
- Perfect 4th - 5. Open, stable-ish.
- Tritone (augmented 4th / diminished 5th) - 6. Highly unstable; wants to resolve.
- Perfect 5th - 7. Strong and stable - the power chord.
- Minor 6th - 8. Major 6th - 9.
- Minor 7th - 10. The bluesy seventh in a dominant chord.
- Major 7th - 11. Dreamy, unresolved.
- Octave - 12.
Learn to hear them, not just count them. Many people link each interval to the opening of a well-known tune.
Other terms you will meet
- Key - the set of notes a piece is built from, and the note that feels like home.
- Tonic - the home note of a key; also called the key centre.
- Scale - an ordered set of notes defining a key or mode.
- Diatonic - belonging to the current key. Chromatic - from outside it.
- Triad - a three-note chord built from stacked thirds.
- Root - the note a chord is named after.
- Inversion - a chord with a note other than the root in the bass.
- Cadence - a chord movement that ends a phrase.
- Consonance and dissonance - stability and tension between notes.
- Tempo - speed in BPM. Meter - the grouping of beats.
- Dynamics - how loud or soft. Articulation - how a note is played: short, long, accented, smooth.
- Motif - a short musical idea that is repeated and developed.
Do this now
- On a keyboard or your DAW's piano roll, play every interval up from C and name it.
- Find the enharmonic name for every black key.
- Write the W-H pattern of the major scale from memory, then build it starting on G. Which note needs a sharp?