[The following is an exact transcript of this podcast.]
At a crowded party, it seems like it would be hard to hear the person you’re talking to over all the clinking glasses, the chatter and laughter. But somehow, your brain filters out all the noise. Scientists have known about this useful ability for over 50 years—it’s called the cocktail party effect. But they’re still trying to figure out how the brain does it. A new study in the journal Public Library of Science Biology hints at an answer.
Neuroscientists played one repeating tone to volunteers, along with a bunch of louder, distracting tones of different pitches. The participants pressed a button if they heard the right tone. Meanwhile, the researchers were monitoring the subjects’ brain activity. Turns out even when the subjects didn’t think they could detect the repeating tone, it still traveled from the inner ear to the auditory cortex. Somewhere after that initial processing, though, it got discarded before the person was consciously aware of it. So all those other conversations at a party probably likewise make it into your brain. But they get thrown away before you’re aware of them. Unless of course, you’re eavesdropping.