diplophonia

di·plo·pho·ni·a

(dip'lō-fō'nē-ă) Vibration of both the ventricular folds and the vocal folds, producing two simultaneous voice tones. [diplo- + -phonia]

diplophonia

(dip-lo-fo'ne-a) [? + phone, voice] Simultaneous production of two different voice tones. Synonym: diphonia