An interesting entry published today on the Scientific American blog The Scicurious Brain discusses our brain's ability to process and distinguish the distance of sounds. The post highlights a recent small study (subscription required) that used fMRI scans to identify if people can determine between the different distances of sounds and the location in the brain where these signals are processed.
In comparing brain activity for distance versus intensity, researchers found important differences in a specific area in the temporal lobe. Scicurious writes:
"...the authors hypothesize that this area, which is also near other auditory pathways known to process things like the direction of sound, might process the distance as well.
What they were relying on to reveal this result is stimulus-specific adaptation. Basically, your brain will show reduced responses to something that is repetitive. A behavioral correlate of this would be, say, entering a room with a white noise generator. At first you notice it, but after a while it recedes into the background and you cease to notice it. Another example would be how most people cease to feel their clothing as it rubs on them during the day (though I bet you’re thinking about it now!). These are stimulus-specific adaptations. They occur easily to things like sound, and the brain will also respond less to such repetitive things. So the authors were hoping that the stimulus specific adaptation to things like the constant condition of noise would allow the delicate differences in distance and intensity to come through."