March 13, 2013
Cocktail Party Science
Scientists led by Columbia University’s Department of Psychiatry have finally started doing science we can all use. Cocktail Party science! Now, they didn’t study booze, or women in skimpy dresses, or even how to get the waiter to bring over the damned tray of hors d’oeuvres without yelling. Maybe they will get to those problems next year.
All kidding aside, they have put out a new study investigating a problem we have all had to deal with; how to focus on just one voice in a crowded room full of talking people. The study, published in a recent issue of Neuron, demonstrates how the brain can hone in on just one speaker in such a situation.
The research team, led by Dr. Charles Shroeder, found that brain waves are shaped so the brain can selectively track the sound patterns from the speaker of interest, and at the same time exclude competing sounds from other speakers. See??? Your husband WASN’T lying when he said he didn’t hear you during the football game; he had just shaped his brainwaves into football shapes, not wife shapes.
The study findings could be important for helping people with a range of deficits including ADHD, autism and aging.
“In hearing, there is no way to ‘close your ear,’ so all the sounds in the environment are represented in the brain, at least at the sensory level,” explains Dr. Schroeder. “While confirming this, we also provide the first clear evidence that there may be brain locations in which there is exclusive representation of an attended speech segment, with ignored conversations apparently filtered out.” In other words, when you are concentrating on hearing the sports scores, you can barely, if at all, hear your mother-in-law.
Dr. Schroeder and Dr. Elana Zion Golumbic, also of Columbia University, and their colleagues from New York University, University of Maryland, and Hillside-Long Island Jewish used direct recording of brain activity in surgical epilepsy patients who were listening to natural spoken sentences. They found two types of effects. In and near auditory cortex, brain signals reflect both attended and ignored speech. Attended speech, however, generates higher signal amplitudes. Representations of attended speech is clear in regions of the brain involved in “higher-order processing” while that of ignored speech was not detectable. As a sentence unfolds, the selective higher-order representation is progressively refined.
“Most studies use very simplified, unnatural stimuli to study the Cocktail Party Problem—like brief beeps, or even brief phrases—whereas we were able show that with appropriate techniques, we could study this problem using natural speech,” says Dr. Schroeder. “This will stimulate future research to continue the study of this and related issues under rich, natural conditions. Just as importantly, the ability to directly analyze widespread brain activity patterns in surgical epilepsy patients provides an unprecedented opportunity to firmly connect the work on the Brain Activity Map at the model systems level in mice, songbirds, and nonhuman primates to the study of capacities like language and music, that may be uniquely human.”
So while Cocktail Party science isn’t as exciting or titillating as it might be, it does give us a good reason for selective hearing.
Image Credit: Photos.com