Key signatures and accidentals are the building blocks of music's tonal language. They work together to create the unique sound and feel of different musical keys, guiding musicians through the harmonic landscape of a piece.

Understanding these elements is crucial for reading and writing music. Key signatures set the tonal foundation, while accidentals allow for temporary pitch changes, adding color and complexity to melodies and harmonies.

Key Signatures and Tonal Centers

Establishing the Tonal Framework

• A key signature is a set of sharps or flats placed at the beginning of each staff line, immediately following the clef symbol, to indicate the notes that are to be consistently played as sharps or flats throughout the piece or section
• Key signatures establish the tonal center or home key of a composition, defining the diatonic scale that forms the basis of the music
  • The tonal center provides a sense of resolution and stability in a piece (C major)
• The key signature applies to all octaves of the notes indicated, not just the specific pitches shown in the key signature itself
  • If a key signature has an F♯, all F notes in the piece will be played as F♯ unless otherwise indicated by an accidental
• The absence of a key signature indicates that the piece is in C major or A minor, as these keys contain no sharps or flats in their diatonic scales

Using Key Signatures with Accidentals

• Key signatures are used in conjunction with accidentals to create a hierarchy of pitches and establish the tonal framework of a piece
• Accidentals can temporarily alter the pitches indicated by the key signature to create chromatic variations or modulations
  • A piece in G major (one sharp, F♯) might use a C♯ accidental to briefly tonicize the key of D major
• The combination of key signatures and accidentals allows for a wide range of tonal possibilities within a composition
• Understanding the relationship between key signatures and accidentals is essential for accurate music reading and interpretation

Interpreting Key Signatures

Placement and Order of Sharps and Flats

• Key signatures are written on the staff immediately after the clef and before the time signature
• The order of sharps in a key signature is always F♯, C♯, G♯, D♯, A♯, E♯, and B♯ (can be remembered using the mnemonic: "Father Charles Goes Down And Ends Battle")
• The order of flats in a key signature is always B♭, E♭, A♭, D♭, G♭, C♭, and F♭ (can be remembered using the mnemonic: "Battle Ends And Down Goes Charles' Father")
  • These mnemonics help musicians quickly recall the order when reading or writing key signatures
• Sharps and flats in key signatures are always written in a specific sequence, with each new accidental added to the right of the previous one on the staff

Determining Major and Minor Keys

• In sharp key signatures, the last sharp in the key signature is the leading tone (7th scale degree) of the major key, and the key is named after the note a half step above the last sharp
  • For example, if the key signature has three sharps (F♯, C♯, and G♯), the major key is A major (G♯ being the leading tone)
• In flat key signatures, the second-to-last flat is the name of the major key
  • For example, if the key signature has three flats (B♭, E♭, and A♭), the major key is E♭ major
• To determine the relative minor key, locate the note a minor third (three half steps) below the major key. The key signature remains the same for both the major key and its relative minor
  • For a key signature with one sharp (F♯), the major key is G major, and the relative minor is E minor
• Knowing how to identify major and minor keys from key signatures is crucial for understanding the tonal context of a piece

Accidentals in Music

Types and Functions of Accidentals

• Accidentals are symbols placed before a note to raise or lower its pitch by a half step, independent of the key signature
• A sharp (♯) raises the pitch of the note by a half step, while a flat (♭) lowers the pitch of the note by a half step
  • For example, in the key of C major (no sharps or flats), an F♯ accidental would raise the pitch of F to F♯
• A natural (♮) cancels a previous sharp or flat, restoring the note to its original pitch as indicated by the key signature
  • If a piece in G major (F♯) uses an F♮ accidental, the F will be played as a natural note, not as F♯
• Double sharps (𝄪) and double flats (𝄫) are used to raise or lower a note by two half steps, respectively. These are less common but may be necessary for certain chromatic alterations or modulations

Scope and Notation of Accidentals

• Accidentals apply to all notes of the same pitch within the same measure, unless cancelled by another accidental
  • If a measure in C major contains an F♯ accidental, all subsequent F notes in that measure will be played as F♯
• Courtesy accidentals, or cautionary accidentals, are sometimes used to remind the performer of the correct pitch, especially when a note's accidental status has changed from the previous measure
  • If a measure contains an F♯ accidental and the next measure starts with an F♮, a courtesy accidental may be used to clarify the change
• Accidentals are an essential tool for creating chromatic alterations, modulations, and expressive inflections in music

Key Signatures vs Scales

Major and Minor Scales

• Key signatures are derived from the pitches of the major and minor scales, with each scale having a unique set of sharps or flats
• The major scale pattern (W-W-H-W-W-W-H, where W = whole step and H = half step) determines the pitches of a major key and its corresponding key signature
  • The key of G major (one sharp, F♯) contains the pitches G, A, B, C, D, E, and F♯
• The natural minor scale pattern (W-H-W-W-H-W-W) determines the pitches of a minor key and shares the same key signature as its relative major
  • E natural minor (one sharp, F♯) contains the pitches E, F♯, G, A, B, C, and D

Harmonic and Melodic Minor Scales

• Harmonic minor scales raise the 7th scale degree by a half step, creating a leading tone that resolves to the tonic. This raised 7th is not indicated in the key signature but is instead notated with an accidental
  • In E harmonic minor, the D♯ is notated with an accidental, while the key signature remains one sharp (F♯)
• Melodic minor scales raise the 6th and 7th scale degrees when ascending and revert to the natural minor scale when descending. These raised pitches are not shown in the key signature but are notated with accidentals
  • In E melodic minor, the ascending scale includes C♯ and D♯ accidentals, while the descending scale uses the natural minor pitches (C♮ and D♮)

Chromatic Scales

• Chromatic scales include all twelve pitches within an octave and do not have a specific key signature. Instead, they are notated using accidentals for each note that deviates from the C major scale
  • A chromatic scale starting on C would be notated as C, C♯, D, D♯, E, F, F♯, G, G♯, A, A♯, B, C
• Understanding the relationship between key signatures and scales is essential for music theory, composition, and performance