Preset group · Notes · A=440
Notes at A = 440. The tuning of almost all music.
Almost all the music you hear today is tuned with the middle A at 440 Hz, the international standard since 1955. This group is the twelve notes of that octave, from C4 to B4.
It's for comparing: any frequency from the tradition makes more sense next to a note. And for playing with a MIDI keyboard and watching the plate answer.
The formulas and the figures in the code.
Equal temperament: frequency = 440 · 2^((i − 9)/12), with i from 0 (C4) to 11 (B4). Each semitone multiplies by the twelfth root of 2, about 1.0595. C4 plays at 261.626 Hz, A4 at 440 Hz and B4 at 493.883 Hz.
That's 12 pure tones, with no ratio or layer. In XY they're drawn against A 440.
One line per preset.
- C4 · 261.63 Hz
261.63 Hz
C4, middle C, where the octave starts.
Physical figure (6, 4) + (6, 2) · No layer
- C#4 · 277.18 Hz
277.18 Hz
C#4, a semitone above C.
Physical figure (6, 4) · No layer
- D4 · 293.66 Hz
293.66 Hz
D4, a whole tone above C.
Physical figure (6, 4) · No layer
- D#4 · 311.13 Hz
311.13 Hz
D#4, a minor third above C.
Physical figure (6, 4) · No layer
- E4 · 329.63 Hz
329.63 Hz
E4, a major third above C.
Physical figure (6, 4) + (8, 0) · No layer
- F4 · 349.23 Hz
349.23 Hz
F4, a fourth above C.
Physical figure (8, 0) · No layer
- F#4 · 369.99 Hz
369.99 Hz
F#4, the tritone, half the octave.
Physical figure (8, 2) · No layer
- G4 · 392.00 Hz
392 Hz
G4, a fifth above C.
Physical figure (6, 6) · No layer
- G#4 · 415.30 Hz
415.3 Hz
G#4, a minor sixth above C.
Physical figure (8, 4) + (6, 6) · No layer
- A4 · 440.00 Hz
440 Hz
A4, 440 Hz: the reference note for almost all music.
Physical figure (8, 4) · No layer
- A#4 · 466.16 Hz
466.16 Hz
A#4, a minor seventh above C.
Physical figure (8, 4) · No layer
- B4 · 493.88 Hz
493.88 Hz
B4, a major seventh above C, the last in the octave.
Physical figure (8, 4) + (8, 6) · No layer
Tab. 01 · Plate figure calculated by the app's core (cym.core.js) for each frequency: a square plate driven at the center, f = 5.5·(n² + m²) Hz. Two modes = the plate answers with both.
The physical figure and the symbolic layer.
In Chladni, C4 draws a blend of modes (6, 4) and (6, 2) and A4 mode (8, 4). Neighboring notes, a semitone apart, can land on the same figure: a plate driven from the center has fewer figures than there are notes.
No layer: it's the plate alone.
What people ask about this group.
Q1Why A = 440 Hz?
It's been the international standard since 1955 (ISO 16). For centuries every city tuned its own way; 440 was picked as a round number close to what was already in use.
Q2How do you calculate a note's frequency?
With equal temperament: each semitone multiplies the frequency by the twelfth root of 2. From A4 = 440 Hz you go up or down note by note.
Q3What changes at A = 432?
Every note drops about 32 cents, less than a third of a semitone. You'll find it in the Notes · A=432 group.