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.
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 |