Scientists believe they have found answers to the mystery of the 'cocktail party' effect in the brain, where a person is able to hear one voice in a room with many speakers.

The new study found how the brain filters out other voices, which has long been a mystery to scientists.

Two researchers at the University of California, San Francisco, studied three subjects who were undergoing surgery for epilepsy.

The subjects, already hooked to electrodes in the auditory regions of the brain, according to the New Scientist, were instructed to listen to only one of two people speaking to them.

The subjects were able to focus on one voice over another despite the competition for the brain's attention.

“That’s one of the remarkable things that humans can do naturally,” says neuroscientist Edward Chang at the University of California, San Francisco, the study's author, according to Nature.

"When the subjects successfully focused their attention, their brain activity showed that they were processing only that voice. It was “as if the other one was not even heard.”

Medical XPress said that the findings are a milestone in understanding how the brain processes language and may have implications for hearing impairment, attention deficit disorder and autism.

The study may also have implications for voice recognitions systems, which may soon be able to hear one voice among many.