A♯ (musical note)

A (A-sharp), or la dièse, is the eleventh semitone of the solfege. In some countries (where B is known as H) it is informally called B.

This note lies a chromatic semitone above A and a diatonic semitone below B, thus being enharmonic to si bémol or B (B-flat).

When calculated in equal temperament with a reference of A above middle C as 440 Hz, the frequency of the A above middle C is approximately 466.164 Hz. See pitch (music) for a discussion of historical variations in frequency.

Designation by octaveEdit

Scientific designation Helmholtz designation Octave name Frequency (Hz)
A−1 A͵͵͵ or ͵͵͵A or AAAA Subsubcontra 14.568
A0 A͵͵ or ͵͵A or AAA Subcontra 29.135
A1 A͵ or ͵A or AA Contra 58.270
A2 A Great 116.541
A3 a Small 233.082
A4 a One-lined 466.164
A5 a′′ Two-lined 932.328
A6 a′′′ Three-lined 1864.655
A7 a′′′′ Four-lined 3729.310
A8 a′′′′′ Five-lined 7458.620
A9 a′′′′′′ Six-lined 14917.240
A10 a′′′′′′′ Seven-lined 29834.481


Common scales beginning on AEdit

Diatonic scalesEdit

  • 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 minorEdit

See alsoEdit