How your brain understands one voice in a noisy crowd

(Credit: Jaybird/Flickr)

Researchers have found a new clue into how the brain is able to intentionally hear one speaker while weaning out or ignoring a different speaker.

In a crowded room where many people are talking, such as a family birthday party or busy restaurant, our brains have the ability to focus our attention on a single speaker.

The brain is actually taking an extra step to understand the words coming from the speaker being listened to, and not taking that step with the other words swirling around the conversation, the new research reveals.

“Our findings suggest that the acoustics of both the attended story and the unattended or ignored story are processed similarly,” says Edmund Lalor, associate professor of neuroscience and biomedical engineering at the University of Rochester Medical Center. “But we found there was a clear distinction between what happened next in the brain.”

For this study in the Journal of Neuroscience, participants simultaneously listened to two stories, but were asked to focus their attention on only one. Using EEG brainwave recordings, the researchers found the story that they instructed participants to pay attention to was converted into linguistic units known as phonemes—these are units of sound that can distinguish one word from another—while the other story was not.

“That conversion is the first step towards understanding the attended story,” Lalor says. “Sounds need to be recognized as corresponding to specific linguistic categories like phonemes and syllables, so that we can ultimately determine what words are being spoken—even if they sound different—for example, spoken by people with different accents or different voice pitches.”

Additional coauthors are from the University of Rochester; Trinity College; University of Dublin; University of California, San Francisco; Boston University; Google Research; and the University of Maryland.

Funding for the research came from the Science Foundation of Ireland, Irish Research Council Government of Ireland, Del Monte Institute for Neuroscience Pilot Program, and the National Institute on Deafness and Other Communication Disorders.

Source: University of Rochester