Very good question. I've dealt with this exact thing. Chords can be "voiced" any number of ways, meaning you can put different notes of the chord on the top or bottom and they'll sound slightly differen even though it's the same chord. If there's a song in F Major, the chorus might sing a chord that's voiced F-A-C-F (from lowest to highest.)
Now presume a new lead actor comes in and we lower the key a fourth to C. Now the chord the chorus sings is C-E-G-C. But that chord is a lot lower and darker sounding.
The solution is to revoice the chord so that it's G-C-E-G. Same chord but a different inversion. (In F, the root is the bottom of the chord. In C, the fifth would be the bottom note in this example.)
So the Sopranos who were singing a high F in the old key are singing a high G in the new key, even though the soloist is singing it lower.
Updated On: 6/30/17 at 09:06 AM