When we talk about "classical music"...

If you haven't guessed already, I'm using both this (recently resurrected) Facebook page and my blog as sort of a free music theory class, only I'm teaching it way differently than they do at conservatories.

You can also teach yourself most of what you'd learn at a university just by reading Wikipedia articles. (But I'd always study further elsewhere.)

There isn't really a set definition of what is collectively called "classical music", so I try to avoid using the term except when talking about Classical-era music (Haydn, Mozart, earlier Beethoven), and use "Western common practice" as a broad term to include the the Baroque, Classical and Romantic eras. (This does not include early music, i.e. the ancient, medieval, or Renaissance eras; nor does it include modern-contemporary music. However, the lines that begin and end common practice are blurry; one has to set an arbitrary date range, such as 1600-1900.)

What unites common practice music? A number of things:

• a chromatic scale with twelve notes per octave; the gradual dominance of equal temperament; quarter tones and other microtonal intervals were never used
• tonality based on major and minor keys, with major and minor scales (for the latter: natural, harmonic and melodic), as opposed to modes in early music and atonality in much modern music
• relatively little distinction between sacred and secular music
• functional harmony, predictable chord progressions and cadences
• divisive meters (simple and compound), rather than additive meters, and a steady pulse and a generally consistent tempo (the usual time signatures were 4/4 or common time, 2/4, 2/2 or cut time / alla breve, 3/4, 6/8, 9/8 and 12/8, with little use of odd meters such as 5/4 and 7/8)
• the virtual disappearance of notes longer than a whole note (i.e. breve, longa, larga); the end of mensural notation and the dominance of modern staff notation
• the establishment of bel canto and the standard tessituras of soprano, alto, tenor and bass voices
• the widest gulf between "high" (art) and "low" (popular and folk) musics; this would begin to be broken down in the modern era

... and so on and so forth.