A♭ (musical note)

${ \new Staff \with{ \magnifyStaff #3/2 } << \time 2/1 \override Score.TimeSignature #'stencil = ##f { \clef bass aes1_A-flat \clef treble aes' } >> }$

A♭ (A-flat; also called la bémol) is the ninth semitone of the solfège.

It lies a diatonic semitone above G and a chromatic semitone below A, thus being enharmonic to G♯, even though in some musical tunings, A♭ will have a different sounding pitch than G♯.

When calculated in equal temperament with a reference of A above middle C as 440 Hz, the frequency of the A♭ above middle C (or A♭₄) is approximately 415.305 Hz.^[1] See pitch (music) for a discussion of historical variations in frequency.

The notes A♭ and G♯ are the only notes to have only one enharmonic, since they cannot be reached in any other way by a single or double sharp or a single or double flat from any of the seven white notes.

Designation by octave

Scientific designation	Helmholtz designation	Octave name	Frequency (Hz)
A♭₋₁	A♭͵͵͵ or ͵͵͵A♭ or AAAA♭	Octocontra	12.978
A♭₀	A♭͵͵ or ͵͵A♭ or AAA♭	Subcontra	25.957
A♭₁	A♭͵ or ͵A♭ or AA♭	Contra	51.913
A♭₂	A♭	Great	103.826
A♭₃	a♭	Small	207.652
A♭₄	a♭′	One-lined	415.305
A♭₅	a♭′′	Two-lined	830.609
A♭₆	a♭′′′	Three-lined	1661.219
A♭₇	a♭′′′′	Four-lined	3322.438
A♭₈	a♭′′′′′	Five-lined	6644.875
A♭₉	a♭′′′′′′	Six-lined	13289.75
A♭₁₀	a♭′′′′′′′	Seven-lined	26579.501

Scales

Common scales beginning on A♭

A♭ major: A♭ B♭ C D♭ E♭ F G A♭
A♭ natural minor: A♭ B♭ C♭ D♭ E♭ F♭ G♭ A♭
A♭ harmonic minor: A♭ B♭ C♭ D♭ E♭ F♭ G A♭
A♭ melodic minor ascending: A♭ B♭ C♭ D♭ E♭ F G A♭
A♭ melodic minor descending: A♭ G♭ F♭ E♭ D♭ C♭ B♭ A♭

Diatonic scales

A♭ Ionian: A♭ B♭ C D♭ E♭ F G A♭
A♭ Dorian: A♭ B♭ C♭ D♭ E♭ F G♭ A♭
A♭ Phrygian: A♭ B C♭ D♭ E♭ F♭ G♭ A♭
A♭ Lydian: A♭ B♭ C D E♭ F G A♭
A♭ Mixolydian: A♭ B♭ C D♭ E♭ F G♭ A♭
A♭ Aeolian: A♭ B♭ C♭ D♭ E♭ F♭ G♭ A♭
A♭ Locrian: A♭ B C♭ D♭ E F♭ G♭ A♭

Jazz melodic minor

A♭ ascending melodic minor: A♭ B♭ C♭ D♭ E♭ F G A♭
A♭ Dorian ♭2: A♭ B C♭ D♭ E♭ F G♭ A♭
A♭ Lydian augmented: A♭ B♭ C D E F G A♭
A♭ Lydian dominant: A♭ B♭ C D E♭ F G♭ A♭
A♭ Mixolydian ♭6: A♭ B♭ C D♭ E♭ F♭ G♭ A♭
A♭ Locrian ♮2: A♭ B♭ C♭ D♭ E F♭ G♭ A♭
A♭ altered: A♭ B C♭ D E F♭ G♭ A♭

References

^ Suits, B. H. (1998). "Physics of Music Notes - Scales: Just vs Equal Temperament". MTU.edu. Michigan Technological University. Retrieved 5 February 2024.