AP Music Theory Unit 1 Notes: Pitch, Major Scales, Key Signatures, and Intervals

Pitch

Perception of how “high” or “low” a sound is; in theory it can be named (e.g., C, F-sharp) and located in a specific octave/register.

Pitch class

All notes with the same letter name (and accidentals) across all octaves (e.g., all C’s).

Staff

A set of five horizontal lines on which notes are placed on lines/spaces; moving stepwise means moving to the next line or space.

Ledger lines

Short lines added above or below the staff to notate pitches higher or lower than the five staff lines can show.

Clef

A symbol at the beginning of the staff that assigns a reference pitch to a specific line, determining what pitches the staff lines/spaces represent.

Treble clef (G clef)

Clef that curls around the G above middle C; used for higher ranges (e.g., flute, violin, soprano/alto voices).

Bass clef (F clef)

Clef that places F below middle C on the 4th line (from bottom); used for lower ranges (e.g., cello, trombone, left hand of piano).

C clef

Clef that centers on middle C; the line the clef points to is middle C (used in alto and tenor clefs).

Alto clef

A C clef with middle C on the middle line of the staff; used primarily for viola.

Tenor clef

A C clef with middle C on the second line from the top; used for some cello, bassoon, and trombone parts.

Grand staff

Two staves (treble and bass) bracketed together, common in piano music, allowing a wide pitch range to be notated.

Middle C

The C between treble and bass clefs: one ledger line below the treble staff and one ledger line above the bass staff.

Accidental

A symbol that alters a pitch (sharp raises, flat lowers, natural cancels a sharp/flat) outside the key signature.

Scope rule (accidentals)

An accidental applies for the rest of the measure on that same line/space and does not automatically carry into the next measure.

Enharmonic equivalence

Two differently spelled notes that sound the same in equal temperament (e.g., F-sharp and G-flat); spelling still matters for theory and function.

Major scale

A foundational scale defined by the whole/half step pattern W–W–H–W–W–W–H, using each letter name exactly once.

Whole step

A distance of two half steps (two semitones).

Half step

The smallest standard distance in Western equal temperament; one semitone (adjacent keys on a piano, including black keys).

Key signature

Sharps or flats at the beginning of a staff indicating which pitch classes are consistently altered throughout a piece (unless changed by accidentals).

Order of sharps

Fixed sequence sharps are added in key signatures: F, C, G, D, A, E, B.

Order of flats

Fixed sequence flats are added in key signatures: B, E, A, D, G, C, F.

Circle of fifths

A map of keys ordered by ascending perfect fifths; clockwise adds sharps one at a time, counterclockwise adds flats one at a time.

Interval

The distance between two pitches, described by size (2nd, 3rd, etc.) and quality (perfect, major, minor, augmented, diminished).

Compound interval

An interval larger than an octave (e.g., 9th, 10th), often understood as an octave plus a simple interval.

Interval inversion

Swapping the notes by moving one an octave so the interval flips; simple interval numbers add to 9 and qualities invert (M↔m, A↔d, P↔P).