Why was the musical scale divided into 8 or 12 equal parts?

Question:

Why was the musical scale divided into 8 or 12 equal parts?

Best Answer - Chosen by Asker: Actually, it is based on what is known as the harmonic series.

Modern music doesn't follow it exactly because one (or more?) of the original notes was (were?) adjusted to sound more pleasing to the human ear.

It goes like this:

Start with a pitch (let's assume C for this example). It is vibrating at its exact frequency, no matter what source (trumpet, guitar, even wind blowing across a pipe... C is C).

Now divide that frequency in half. Repeat this process until you come back to C one octave higher.

That is the harmonic series, and that is the structure that gave us western music.

Sometime ago, it was decided to adjust at least one pitch for the sake of audience approval, and what we were left with survives today.

One other thing... music from other cultures does not always follow this. The most prominent example is music from India, where they distinctly recognize many more notes that we have no way to refer to, except by the blanket designation of "quarter-tones" which means any deviation in pitch of less than one half-step (C to C# is one half step).

Hope this helps.