Is there a term for how many measures a melody should be. I know it sounds off to have a certain amount of measures like 5 because the ear tends to hear in 4 and 12 and others as well. If there is a term for this or any info i can read on this please let me know. i'm more concerned about finding out about some odd things that i see in pieces where they throw in one measure to split up two four measure sections and am wondering if there is some kind of outline to look at.
There is no such thing as 'how many measures a melody should be'. This strict 4x4 (2x2) squareness is an ideal of the galant and classical eras, and the good composers of each of these respective periods rarely adhere to such a formula.
There are phrase-structural theories that use these 'perfect' proportions as archetypes against which all else is compared; however, they simply represent a simple frame of reference. Thus, the opening eight measures of Beethoven's Op. 2 No. 1 sonata is generally regarded as the archetypal sentence structure (2 bar basic idea - repeated over dominant harmony - continuation phrase of 4 measures that includes fragmentation, 'liquidation', and a cadential progression).
I think the most succinct and applicable theory to date (in terms of what you seem to be looking for) is that put forth by William Caplin in his book entitled Classical Form. The book is quite expensive, so if you would like, I can give a mini course online using his text as a reference. This would give you the up-to-date terminology, along with a better understanding of classical form, complete with examples from the repertoire of Haydn, Mozart, and Beethoven.
I don't mind doing this, but it's only worth the time if you are sincerely interested.
Let me know.
- Andrew