25 April 2012

The Cocktail Party Effect Explained

We've all been there, a loud and buzzing cocktail party. For once it is not the volume of the music but the sheer number of conversations and background noise going on all around that impedes your conversation. You somehow manage to filter out the residual racket and focus in on your immediate conversation. With the aid of a humanoid robot, scientists have now found  new clues as to how we get around "The Cocktail Party Problem".

The study took place at NNT Communication Science Laboratories in Kanagawa Japan. Volunteers were asked to sit alone in a small room facing a speaker. Participants were then played a combination of two different tones. The tones first appeared as you would imagine a loud party would and the noise came as a mash of sounds. After a short few seconds participants were able to decipher one tone from another. 

The team of scientists then turned to their robotic assistant. The idea they were testing was, if head movements could reset the cocktail party effect i.e AFTER we've filtered the melange of noises does turning your head reset it. 

Sound reaches our ears in different ways depending on our head movements, and the robotic assistant with a humanoid head, had built in microphones designed to mimic how humans hear. 

Now the real experiment started. The participant and robot were placed in separate rooms and then the two-toned sound relayed from microphones in the robots ear canal. The researchers would then instruct the volunteer to turn their head at various point in the experiment. The robot would mimic these head movements which meant the researchers were able to isolate the consequences of head movements on the cocktail party effect. Variations ranged from - the source of the sound changing, only head movement changed, and some with both. 

Results showed that rapid head motion resets the cocktail party effect, however simply changing what we are paying attention to, i.e where our eyes are focused, does not. However, after being reset our brains begin to sift out the noise once again within a few seconds.

In short - a quick turn of the head makes us reset our perception of what we're hearing. 

One scientist from New York University, describes the research as being "highly novel" and cites the key results as being the most sup rising, he says

“If you move your head such that the acoustic stimulus at the ears changes, but the environment itself doesn’t, you wouldn’t have thought you would need to restart the process of interpretation,”.

So next time you need to tune into the conversation in the group next door or find yourself not listening, give your head a casual swivel and reset to tune in once more. 

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