Humans can learn "sequential structure from multiple sources at the same time, as long as the sensory characteristics of the sources do not overlap," Christiansen said.
IOW, We can listen to a car radio and drive while keeping an eye on changing traffic conditions -- separate complex tasks completed without much trouble. But if two people are talking to us at the same time, our perceptual frequencies get jammed, says a new study.
3. DoubleTalk: Funz Fun - Durwood "Mr. Doubletalk" Fincher