GRIFTY wrote:can the modes be in key with each other?
for example.... if i play in B 'locrian' (which if i understand correctly would be BCDEFGAB) would i still be in tune with C ionian? which would be the "true" key?
If you play in B Locrian your key is B
If you play in C Ionian your key is C
That's two different tonal centers. B and C.
There's a thing called bitonality that involves having two keys at the same time, but that's an advanced concept and usually reserved for esoteric music.
You will notice that if you try to improvise something in B Locrian there will be some tendency to end up in C Ionian - that's because some keys are weaker than others (for reasons such as miahluvdd explained). Locrian is not a good example. Strongest is Major (Ionian), next is Minor (Aeolian), preferably in it's harmonic variation. Use those for some examples for your idea. (But let's leave the Harmonic out of this - it doesn't fit into the usual modes)
Play C Ionian and A Aeolian at the same time. Which is the true key? Weird question hey? Can you tell while playing? 2 simple rules to tell the real key:
1) it's the first and the last chord (meaning, music begins and ends in C chord, C is the key - notice I'm not saying if the chord is major or minor, doesn't matter, see below)
2) If you play the note all the time during the music it doesn't sound that bad
(as with every rules, there's always exceptions, and rely more on 1 than 2)
But is it C major or C minor? Look at the 3rd note of the scale:
a) Eb - then it's C minor
b) E - then it's C major
To get a good grasp of all this get in front of a keyboard:
1st) With Left hand keep playing always the A note for bass, with right hand improvise something using several white keys. Start in A note, do it for a while, end in A note.
2nd) With Left hand keep playing always the C note for bass, with right hand improvise something using several white keys. Start in C note, do it for a while, end in C note.
Summary:
If you play in A Aeolian your key is A
If you play in C Ionian your key is C
Let's got for a weirder experience: Let's try C Aeolian and C Ionian at the same time.
Is this bitonality? no and yes. No because, the tonal center is the same, C, thus just one. Yes, because the "flavor" is too different, one scale is minor the other is major.
You will also notice that if you use the C Ionian for the chords and the C Aeolian for the melody there are some resemblances with blues...