# Term for conversion between different tonalities (C major to C minor, etc.)

(Inspired by this recent question:)

If we theorists reserve "transposition" for shifting everything by specific intervals, like every note goes down by a minor 3rd, what do we say when someone transforms a piece in C major to C minor (like by lowering the thirds, etc.) or also potentially shifting everything by generic intervals (CDEFG becomes DEFGA, shifted by diatonic 2nds in the C major scale)?

Is there a term for this that I forgot or cannot recall? Or is there no specific term besides "converting", "transforming", or other general terms?

• "Relative and Parallel Keys" might be the words you look for. I don't understand them enough to write an answer.
– Emil
Feb 3, 2020 at 20:34
• If you stay inside the cyclic group another generic term might be permutation (or group action if it acts on another set)
– Emil
Feb 3, 2020 at 21:30
• Isn't that a reharmonization? Feb 4, 2020 at 0:35
• I'm not convinced, that this process is done frequently enough to have established a well-known word. One reason for this is, that not much of the character of the piece can be preserved during this process. Feb 4, 2020 at 11:21

I think you first want to use the wording change of mode to capture the major to minor change. You often read something like "...a change to the minor mode..."

Modulation is not a good choice, because the meaning of that word is very clear, and means only a change of tonic without any indication of what happens in the new tonic. I think the typical usage of modulate carries the expectation that new thematic material is presented in a larger form. You don't modulate a whole song from one tonic to another. A work modulates to a new tonic and introduces a new theme. That is the typical usage.

In contrast to transpose - changing the tonic, but not the mode, like Over the Rainbow in `A` flat major transposed to `D` major - the wording reinterpreted in minor may be a good choice. Over the Rainbow reinterpreted in `G` sharp minor.

I think reinterpret captures the important point that choices need to be made about which tones get changed. Putting the music into the minor mode is not as simple as changing only the major third of a major key to a minor third. The sixth and seventh scale degrees are variable in minor, and while there is conventional handling of those two degrees it isn't a matter of hard and fast rules. Different choices could be made for different expressive reasons.

Translation seems like a good description too. When a write translates a work of literature from one language to another choices are made for one wording over another. Two translators could translate the same book differently. The same could happen translating a musical work from major to minor. Two musicians could translate the music differently.

This is called Modulating to a parallel key. Reference: https://www.musicnotes.com/now/tips/a-complete-guide-to-musical-modulation/.

Extraneous modulation is going from one key to an unrelated one. Parallel modulation would be a good term for going into the parallel major/minor.

The theory term must be modal interchange.

Like a borrowed chord is an example of modal interchange we have here the case that the whole scale adapted to the tune is modal changed.

https://music.tutsplus.com/tutorials/introduction-to-modal-interchange--audio-14142