I think that neuroscience can help explain.
Neuroscientists have confirmed what we have long known -- that there is an important difference between hearing and listening. In this nice little piece by Seth Horowitz, a Brown University neuroscientist, we learn that the auditory sense is quantitatively almost 10 times faster than the visual sense. In other words, our reactions to what we hear are less processed and more instinctive than our reactions to what we see. Horowitz describes the auditory sense as the human "alarm system" that operates constantly, even while asleep.
To balance that constant guardedness, we have something like "volume control" -- a way of turning up important sounds and diminishing less important sounds. This volume control is the attention. The philosopher/psychologist William James described it in the Principles of Psychology in the following way: "Everyone knows what attention is. It is the taking possession by the mind in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought...It implies withdrawal from some things in order to deal effectively with others, and is a condition which has a real opposite in the confused, dazed, scatterbrained state."
The difference between hearing and listening is, of course, the quality of attention. Horowitz distinguishes between the startle, which is attention in its most attenuated, alarm-sounding, and reactive form and what he calls "stimulus directed attention." While the startle form of attending involves relatively little brain function and has been observed in every animal that has a spine, stimulus directed attention is much more complex and works through "temporoparietal and inferior frontal cortex regions, mostly in the right hemisphere." According to Horowitz, these are areas of the brain that are outwardly concerned; i.e. they are less interested in protecting the organism from danger and more interested in observing and understanding the stimulus received from the outside world. This is the sense in which they are "stimulus directed."
While hearing perhaps originated as a sort of alarm system, in the human brain it can be hooked up into a much more complex, outward oriented, and stimulus directed form of attention. When this happens, we say we are listening, rather than hearing.
Horowitz does a nice job of linking the neuroscience up with social concerns, particularly our interactions with media and with each other. It seems pretty clear that part of our political divisiveness has to do with the way our forms of attention are activated through media.
But I want to turn to running as another realm in which this distinction is important -- and as a realm in which the more complex modes of attention can be developed and trained. Experienced runners, to the chagrin and confusion of new runners, often speak of learning to listen to the body as a key, if not the key to proper training. I think that this Horowitz piece helps to articulate what exactly is meant here.
The art of listening to your body is really an art of developing more complex attention. When we start off in a sport or a new endeavor, we encounter all sorts of new "noises" in our environment, and the most natural reaction to these new stimuli is to be startled by them. The normal feelings of running -- because of their unfamiliarity -- get processed by the reptilian brain as startling, and they generate a fight or flight response. The "flight response" is usually the one activated in runners for obvious reasons, and so the new runner has a tendency to get out there and run to exhaustion on every single run.
But these runs are not the relaxed and confident runs of the well-trained experienced runner. They are painful and somewhat panicked. So, the new runner goes to the message boards and learns that they must slow down and run easy. This works for a time because it diminishes the sensations of running to the level that they can be processed and learned and hooked up to more complex modes of attention.
Once this has been accomplished, and the runner learns how to approach running in a relaxed way, new stimuli need to be introduced gradually and deliberately. This is where having a coach can be really helpful, as he or she can help the athlete distinguish between different modalities of effort and develop the organ of attention. And, in my opinion, this is where overuse or improper use of technologies like heart rate monitors or Garmin pace alerts can impede the development of attention -- in precisely the ways that new forms of media can inhibit the development of the sort of listening that leads to good communication.
I truly believe that in addition of course to genetic differences in talent, the ability to pay attention to one's effort while running in this richer and more complex sense of "listening" is what separates the best runners from the rest. Runners like to talk about pain tolerance and toughness as what makes a race effort full and complete, but the best way to tolerate pain is to understand it as a type of sensation that includes information. This is different from the traditional question of whether we should associate with the pain or disassociate from it to achieve a state of mental toughness.
True mental toughness is less rigid and inflexible than we often imagine it to be. It looks more like the complex attention that Horowitz describes. It looks like calm alertness in the face of the sensations of effort. That's what is meant by "listening to the body."