The frequency of notes/pitches on either end of an octave; e.g.,
C4-C5 or F4-F5 have a 1:2 ratio.
For example, if A4 is 440.00 Hz, A5 is 880.00 Hz.
In so-called equal temperament scaling
the ratio of each pitch to the next pitch; e.g., C-C#, E-F, or
F-F# is constant; For example:
C / B = 523.25 / 493.88 = 1.059
F / E = 698.46 / 659.26 = 1.059
F# / F = 739.99 / 698.46 = 1.059
We can compute the frequency of each of the 12 pitches in the equal temperament scale with the formula:
base frequency * 2 (n / 12), where
n is the number of the pitch (see Pitch nr in the table below)
We could, of course, decide to use equal frequency intervals instead of equal frequency ratios. In
that case we would compute the frequencies as:
base frequency + (n * (base_frequency / 12)
If we would do that, however, our music would start sounding 'off.'
The tables below illustrates both ways of creating the scale (the white fields are buttons that play the corresponding
sounds). The plot shows the differences. Note that the biggest differences occur in the middle of the scales.