A question about music 'parts'

[wanttolearn]

Hello everyone
I am a very new piano student and have a question that I have not had satisfactorily answered to date.

Let us say I write (compose) the melody for a common metre song - e.g., 'Crimond' (The Lord is my Shepherd). My question is: must the other 'parts' for this particular tune (e.g., bass) follow a prescribed formula, or do I (as composer) have the liberty to write whatever music I like for those parts, provided it remains in the correct key (and sounds nice)?

Essentially, my question is this: does any given song have ONE and ONLY ONE tune for a particular part (e.g., bass), that can be mathematically worked out and that cannot be altered; or is the 'tune' of the different parts subject to the whim of the composer? If the latter, wouldn't that mean there are technically an infinite number of possible part tunes?

I know this is a very basic question, but I am very new to all of this...

Thankyou very much. 

[nipohc]

hi wanttolearn


I guess it depends on what "style" of music you're wanting to compose.For chordal hymn like pieces there are certain guidelines to chordal progressions, because they move smoothly and sound good. For example the upper part will have the tune mostly, while the other parts provide chordal basis, the bass part might jump more but it is very important in establishing the chord.

However the guidelines are just guidelines, Bach never followed strict 4-part rules and nor did Beethoven with his modulations. So you're right there are an infinite number of possible tunes, thats why we have an infinite amount of beautiful melodies and chordal progressions in classical music.

It would be worthwhile learning the basics from the guidelines, or looking at musical examples to find out what works and what don't, but no, you don't have to compose rule by rule goodluck!