Carillon defines a carillon as "A musical instrument composed of tuned bronze bells which are played from a baton keyboard. Only those carillons having at least 23 bells may be taken into consideration." The Guild of Carillonneurs in North America (GCNA) defines a carillon as "a musical instrument consisting of at least two octaves of carillon bells arranged in chromatic series and played from a keyboard permitting control of expression through variation of touch. A carillon bell is a cast bronze cup-shaped bell whose partial tones are in such harmonious relationship to each other as to permit many such bells to
A♭ (musical note) 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) 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.