Researchers discovered that brain waves are shaped so that the brain can selectively track the sound patterns from the speaker of interest and at the same time exclude competing sounds from other speakers. The findings could have important implications for helping individuals with a range of deficits such as those associated with attention deficit hyperactivity disorder, 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 senior author Dr. Charles Schroeder, of Columbia University's Department of Psychiatry. "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 this way, when concentrating hard on such an "attended" speaker, one is barely, if at all, aware of ignored speakers.