A♭ (musical note)
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♯, although 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. See pitch (music) for a discussion of historical variations in frequency.
A♭/G♯ is the only note to have only one other enharmonic.
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