Have you ever wondered how in a crowded restaurant, a loud party, a sporting event or any other noisy crowd you can focus in on one voice and all the other voices and noises become muddled in the background? This human ability has been dubbed the Cocktail Party Effect.

In an interesting study, researchers at Queen’s College in Ontario found that long-time married couples can pick out and focus on their partner’s voice more effectively than they can a stranger’s voice. However, the reverse also was found to be true – the couples could also more easily ignore their partner and focus on other voices.

Given all the loud sound waves bouncing around, how is it that one particular voice can be focused upon and the others filtered out? We have the ability to do this when the voice we are focusing on is no more audible than the voices around it. It may seem simple but it is an exceptional ability. Machines using voice recognition programs have not been able to effectively emulate this human ability.

The cocktail party effect has been known since the 1950s but only recently has the exact mechanism been uncovered. Research published in 2012 in the journal Nature identified the mechanisms in the brain responsible for the cocktail party effect.

The researchers, Nima Mesgarani an electrical engineering post-doc, and Edward Chang, a neurosurgeon, both at UCSF, investigated the brain activity of epilepsy patients as they listened to two voices at the same time. The volunteers each had severe epilepsy and were undergoing procedures to map their brains prior to brain surgery to cure the epilepsy. From Science Daily: “Part of this surgery involves pinpointing the parts of the brain responsible for disabling seizures. The UCSF epilepsy team finds those locales by mapping the brain’s activity over a week, with a thin sheet of up to 256 electrodes placed under the skull on the brain’s outer surface or cortex. These electrodes record activity in the temporal lobe — home to the auditory cortex.”

While their brains were being mapped, the volunteers listened to two voices at the same time and asked to focus on one voice or the other. Using data from their brains, the researchers were able to create a decoding algorithm that could replicate how the volunteers focused on one voice or the other. The researchers were then able to tell from activity of brain neurons which voice the volunteers were listening to. Amazing.

This research could have far–reaching effects. It helps us understand how the brain works in terms of auditory processing, may be able to assist in creating brain-controlled prosthetic devices and could lead to huge improvements in voice recognition technologies.