Sunday, February 15, 2009

I hear you had a hair cut?!

Sensory illusions help us understand better how our perception works. Among visual illusions that enabled us to explain the complex functioning of visual pathways, there are also auditory illusions. Audition not only permits us to hear recognizable sounds, music and receive language input, but it is also cleverly processed by the brain. As we have two eyes to see, which enable us to perceive the world in three dimensions, we also have two ears. These two are useful to locate sounds in our surroundings. Specific temporal areas of the brain basically process and calculate the time it takes for a specific sound to arrive to each ear. That delay of time between each ear’s reception of the sound gives the brain enough information to locate the sound's source.

I believe that it is also this phenomenon that explains in part the Cocktail Party Effect. This effect occurs when in a crowded room we are able to filter sound and listen to a specific conversation across that room without interference of the other conversations or sounds. Since you can locate specific sounds by a bottom-up process, it would be logical that you can target a specific sound coming from a specific place by a top-bottom process. However, this would become even more complicated when the source of the sound is in motion...

Thus, I'll stop my brain-storming here and introduce you to the beauty of the auditory system by presenting this nice audio file (I strongly encourage you to put headphones on!):

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