i read it in a web and i try, i like it.

need a vocal track, clone it. rise the fader of one of those, now compress excesivelly say 8.1 and the other vocal track send in pre fader mode to a reverb and balance them. and voila you got it, a good level in the mix and the expresion in the effect...
or viceversa works too, but i prefer the first one.

Very nice, try it three times too
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Recording Studio Suntans