Sorry if this is a silly question, I'm a total newbie to music and trying to wrap my head around things. :)
From what I've learned, there is a pattern to all major/minor scales. For example, a major scale follows the pattern tone-tone-semitone-tone-tone-tone-semitone. For minor scales there were several variations depending on which type of minor scale you used.
So, like, a C major scale starts on C and follows this pattern, thus resulting in notes C D E F G A B. A D major scale starts on D and, following this pattern, results in D E F# G A B C#. Etc.
Now, any piece of music can be rewritten (transposed) to a different scale that follows the same pattern as the original simply by shifting all the notes by a certain amount of semitones. So, take a piece of music in D major, shift all notes down by 2 semitones, and you've got that same piece in C major.
What I don't understand is - unless you've got absolute hearing or are listening to the pieces side-by-side, you won't hear any difference between the two versions. It'll sound exactly the same, even to the most trained ear. So why bother with it? Why are there so many pieces of music in different scales when you could just transpose them all to the same scale?
Some ideas that I came up with on my own but wasn't convinced:
- So that writing is simpler. But no - as long as you don't stray from the notes in the scale, you don't need to use any extra signs. Those are only used when you use notes outside the scale, thus they will be there in the same places no matter how you transpose.
- To match the available range of a specific music instrument/voice. However they all span at least a few octaves, so why would you need to adjust so precisely? Just move them up or down by a whole octave. Unless the piece has a so wide range of sounds that it spans nearly all of the available sounds on the instrument/voice, but I think that's a pretty rare case. And anyway, most of those odd E-major-whatever pieces are for the piano which has the biggest range of them all.
- When playing together several instruments, you might wish to have them play the same melody just a few (semi)tones apart for some specific effect. But then why do these scales then appear for pieces that are meant to be played solo (including all the piano exercises)?
- Because some combinations of notes are easier played (as in the mechanical finger motion is simpler) in a specific scale. Doesn't seem convincing though, most instruments are pretty uniform, and it doesn't apply to voice at all.
So... is there a better explanation as to why so many different scales are employed today?