Saturday, March 28, 2009

Virtual Barbershop auditory illusion

We've all heard of optical illusions - our eyes playing tricks on us. Here is a very famous one, which many of you must be familiar with :
It looks like Albert Einstein alright, but get up off you seat and take a few steps back , about 15 feet back, and someone else very familiar will come into view

And there are many more such optical illusions and we've all seen so much of them. But have you heard of auditory illusions? Your ears tricking you to hear the equivalent of surround sound ( or even better ) when there's only two physical audio sources - your headphones to be precise. Sosit back, relax, close your eyes,  put on your headphones ( it simply doesn't work with speakers ) and play the following clip. 

How does it work? Well we have only two ears anyway, but we can still pinpoint the exact location of sound. It has all to do with the positioning of our ears, the difference with the level of sound reaching the ears, and the way our brain interprets those differences. To record the above auditory illusion , two microphones are placed at the exact position where your ears might be i.e approximately 3.5 inches apart, and the same sound is played back to you at about the same position i.e directly positioned in/on your ears via headphones. Your brain does the rest just as if it is hearing the audio from the original sources. Such recordings are deemed as Binaural Recordings.