14 DAY TRIAL // The way in which the brain manages to focus our attention on a single voice in a room filled with people is something that scientists have been trying to understand for a long time. A new study may have just provided new insight into this mystery.
Chatter and background noises are all around us everywhere we go, yet we are always able to hear the person we're talking to at any given time. In fact, most of the time, all sounds produced around us become muffled, and non-intrusive to our conversations.
The human brain is capable of focusing on a single speaker or voice in a huge mixture of sounds and noises. Understanding how this happens could contribute to the development of new series of treatments for people who lose this ability with age, Science News reports.
University of Minnesota auditory neuroscientist Christophe Micheyl, who was not part of the research, believes that the data gathered in this particular investigation will be of great use for deepening our understanding of how the human auditory cortex works.
The research was conducted by experts at the University of California in San Francisco (UCSF), who were led by engineer Nima Mesgarani and neurosurgeon Edward Chang. They subjected test participants to the “cocktail party problem,” which involves listening to someone while another person also speaks.
The team used a number of epileptic patients for this study, because these individuals have electrodes implanted under the skull. The UCSF team hijacked these signals in order to monitor neural gamma waves. The intensity and patterns displayed by these waves indicated the sounds subjects focused on.
“We are able to assess what someone is actually hearing – not just what’s coming in through their ears,” Chang explains. Participants were asked to listen to two speakers making non-sensical statements, and to remember whatever data each of them said after uttering a certain code word.
Brain wave analysis revealed chaotic patterns throughout the auditory cortex, as the test subjects were listening to both speakers at the same time. When one of the speakers said the code word, researchers could observe in real time how participants' attention snapped to that person, ignoring the other.
“What we found was quite striking. The brain was robustly encoding only the one we are attending to,” Chang explains. Details of the new study were published in the April 18 online issue of the top scientific journal Nature.