Yeah, piggybacking off this post!
@ritardando, you told me to listen to WAKANA's part in Alleluia. I understand what you mean - it is known as the "chorus" effect (in Adobe Audition, at least) that is used to mimick the effects of a full chorus, i.e. multiple singers singing at the same time. So one voice gets split into maybe 2 or 4 voice tracks, each one maybe a millisecond apart from each other so it sounds like multiple singers have participated, and is spanned across the STEREO field to give a grander, more dynamic tone to the vocals. It is mostly used for harmonisations (lower and, some times, upper). Another way to use this effect is for one singer to record a line
twice, and then putting them together; one vocal track will be "left" track, the other will be "right" track. The combined effect will be this "chorus" effect.
I hear this effect being implemented for KEIKO's harmonisations. I don't hear it for any of the other vocalists. The combination of HIKARU+WAKANA in the first two refrains and HIKARU+KEIKO in the final refrain may sound like this effect, but it certainly is not. It is
actually two singers singing the same melody at the same time.