harmonizer

from WordNet (r) 3.0 (2006)

harmonizer
    n 1: a musician who sings or plays in harmony [syn:
         {harmonizer}, {harmoniser}]
    2: a mediator who brings one thing into harmonious agreement
       with another [syn: {harmonizer}, {harmoniser}]

from The Collaborative International Dictionary of English v.0.48

Harmonizer \Har"mo*ni`zer\ (-n[imac]`z[~e]r), n.
   One who harmonizes.
   [1913 Webster]