thats a good article

but to shine a little light on this in reference to Solfeggio

The 6 frequencies are 396, 417, 528, 639, 741, 852. And is often illustrated on a 9 point circle with the addition of 963, 174 and 285. The 396 at the 9 position.

the center digits are 1 thru 9.

Each frequency is a family group.

we can see in the solfeggio that all the 1,4, 7's are division in order, and the 2, 8 and 5's are multipying with 3, 6, 9's moving anticlockwise (division).

Multiply Constant Divide
147 = 3 = 174
285 = 6 = 258
369 = 9 = 396

471 = 3 = 417
528 = 6 = 582
693 = 9 = 639

714 = 3 = 741
852 = 6 = 825
936 = 9 = 963

Each note or frequency has its own unique scale. Equal tempered cromatic scale was invented to make instruments sound ok when played in any key. However in nature, the natural resonant harmonics or overtones that accompany every note, define a unique scale for that single note.

to further give you a example an instrument tuned to C with Just scaling, will have a different B note frequency than the standard modern equal tempered cromatic scale

Note Jus Equal Diff.
C4 261.63 261.63 0.00
C4# 272.54 277.18 4.64
D4 294.33 293.66 -0.67
E4b 313.96 311.13 -2.83
E4 327.03 329.63 2.60
F4 348.83 349.23 0.40
F4# 367.92 369.99 2.07
G4 392.44 392.00 -0.44
A4b 418.60 415.30 -3.30
A4 436.05 440.00 -3.95
B4b 470.93 466.16 -4.77
B4 490.55 493.88 3.33
C5 523.25 523.25 0.00

yet another way of looking at the scale would be ound in the teachings of G.I. Gurdjieff, who is said to be the first to present the enneagram to the west. Much of his teaching was based on the concepts revealed through the movements of energy expressed mathematically in the decimal divisions of seven, which he related extensively to the octave.

According to Gurdjieff, as the octave progresses there comes an interval between mi and fa which must be bridged by the 'do' of another octave, and another 'do' bridging that second octave's mi-fa interval, eventually allowing the first octave to complete only by considering the interaction of inner octaves. Like this ...

nine is Do(1)
one is Re(1)
two is Mi(1)
three is Do(2)
four is Fa(1), Re(2)
five is Sol(1), Mi(2)
six is Do(3)
seven is La(1), Fa(2), Re(3)
eight is Ti(1), Sol(2), Mi(3)
nine is Do(1)
one is La(2), Fa(3)