Resolved Question

Granted the two hemispheres communicate with each other...?

but given the right and left side of the brain coordinate different activities - Do you think that people might listen to and respond significantly differently to aspects of a telephone conversation depending on which ear they hold the receiver to?

This is a really interesting question. But, I would have to say that the answer is probably no. I say probably, because the brain is an elastic and highly maluable thing. It's wiring and activities can vary greatly from individual to individual and since it is all basically software, anything is possible.

But, in a "normal" brain, the only reason evolution has favored two ears is that it gives us a stereophonic auditory image of the world around us. This gives us the advantage of being able to determine the direction and distance of the source of a sound.

However, once an auditory signal is routed into the areas of the brain that process these signals and make "sense" and meaning of the words which are being heard and interpreted, it is likely that the signal from both ears is routed to the same areas that are used for processing of the input.

I think that there is still a great deal that we do not understand about the workings of the brain and the nature of intelligence. Furthermore, it may be that, the plasticity of the brain makes it truly impossible for us to ever know everything because it is not finite. But, I do think we will get closer soon. And I strongly suspect that this will happen once neuro-scientist and those working in the field of Artificial Intelligence begin working together to produce sentient machines.